A Day of My Life, or Everyday Expert* Cloth, lr.mo, pp. 184.. 1 00 

Adams. New "Wall Map of the State of New York, 68x74 inches, cloth 10 00 

Agalite Slating for Black-boards. To cover 50 feet, one coat, POST-PAID. 1 ('0 

Aids to School Disci pliue. Per box. 1 23 

Supplied separately; per 100 Merits. 15 cts; Half Merits, 15 cts; Cards, 
15cts; Checks, 40; Certificates, 50 cts. 

Air Test Bottles. Per set of 8, In cloth case 1 00 

Aldcn (Joseph) First Principles of Political Economy. Cloth, 16mo, pp. 153. 75 

Bales (C. B.) The Diacritical Speller. Boards, 8vo, pp. 68 50 

Kardeen (C. W) Common Sclu-ol Law. Cloth, 16mo, pp. 120 75 

Roderick Hume. The story of a New York Teacher. Cloth, 16mo, pp. 296. 1 25 

Verbal Pitfalls. A manual oi 1500 misused words, Cloth, 16mo, pp. 223.. . 75 

Some Facts about our Public Schools. 8vo. pp. 3d 25 

Educational Journalism. 8vo, pp. 30 25 

Teaching as a Business far Men. 8vo, pp. 20 23 

The Teacher's Commercial Value, 8vo. pp. 20 ". 25 

The Present Status of the Township System. 8vo, pp. 44 25 

Dime Question Book, on Temperance. 16mo. pp.40 10 

Dime Question Book on Bookkeeping. 16mo. pp. 31 10 

Dime Question Book on Letter- Writing. 16mo, pp. 30 10 

A Brief Geography of Onondaga County. lGmo, pp. 48, with Map 25 

The School Bulletin Year Book, 1885. ltimo. interleaved, pp. 160 1 00 

Bassett (J: A.) Latitude, Longitude and Time, Manilla, 16mo, pp.42 25 

Beehe (Levi N.) First Steps among Figures. Cloth, 16mo, pp. 326 100 



Pupil'' B«* 
Bennett l 
Blanebaj 
Bradford 
Brown (C 
Brown (J 
Brown (I.. 
Brownell 
Buckhiiii 
Bugbee, 

Key t 

Bulletir 

BooW 

Book, 

Ce>mp 

— Class 

twenty 

(c) Lik 

School 

-Pencil 



QLath 1fi>> 



LIBRARY OF CONGRESS. 

Shelf- A 6^ 

UNITED STATES OF AMERICA. 



__0, pp T 34 ... 






smo, pp. 100 
too, pp. 1G2. 



look 



48 

15 
3 00 

25 
25 
1 00 
85 
75 
35 
35 
15 
15 

15 



li "per 100,. 



. 25 

35 

100 



Bnrchard (<). H.) Two M < *p. 168 

Bnrritt (J. L.) Penmanship in Public School*. l2mo, 

Canfieid Ttu Opportunities of the Rural Poor for Ilia I: 

ion . I'm per. Svo, pp. 21 15 

Catalogue of 8500 fl fixers. 8vo,pp.72 25 

Chene- be Manual for Schools. Paper. 16mo, pp. 95 

Civil Service Question Hook. l6mo, cloth, pp. 282 

Co.'e of Public J list ruction, S t 4 00 

Colored Crayon, for Blackboard, per ii'»x of one dozen, nine color- 
Collins 

ComPTiiiis, OrbisPictuS. Cloth, Pp.232 3 00 

Comfort (Geo. F 1 Modern Lar\ • lucatum. Paper, 16n 

Comfo 1 Orthographic and Isometric Proj ... 75 

Constitutions, United States and New \ 
Cooke (Sidney G.) Politics and School*. Pai • 
Craig (Asa if) The Common School Question Hook. Cloth, 12mo, pp. 34 

Cube Ko«>t Blocks, carried to 8 places 1 no 

Cyciop;p<iia of Education. Cloth, 8vo. pp. 662 

Davis (\v. W.) Suggestion) for / . l2mo, pp. U 

— * Vr actional Avnaratus, In box 400 

De Graff iv. v.) Practical Phonics. Cloth, 12mo, pp. 108 75 

Pocket Pronunciation Book Manilla, 16mo, pp. 47. ... 18 

The School-Room Guide. Thirteenth Edition. Cloth, i2mo, pp. 449.... 1 50 



C, W. BARDEEN, PtTBLISHER, SYRACUSE, N. Y. 

Development Lessons. Cloth, 8vo., pp. 301 1 50 

The Song Budget. Paper, small 4to, pp. 78. I20£7i thousand 15 

The School-Room Chorus. Boards, small 4to, pp. 147 85 

Calisthenics and Disciplinary Exercises. Manilla, 16mo, pp. 39 25 

De Guimps (Roger). The Life of Pestalozzi. Cloth, 12mo, pp. 331. 1 50 

Denominational Schools. Discussion at the National Educational Asso- 
ciation, 1889, by Cardinal Gibbons, Bishop Keane, Edwin D. Mead, and 

John Jay. Paper, Svo, pp. 71..... 25 

Diplomas, printed to order from any design furnished. Specimens sent. 

(a) Bond paper, 14x17, for 25 5 00 

'* •« 50 650 

(O) " " 16x20," 25 ..5 50 

"50 7 50 

(c) Parchment, 15x20" 5 6 00 

Each additional copy 75 

Education as Viewed by Thinkers. Paper. 16mo, pp. 47 .. 15 

Elocutionist's Annual. Paper, 12mo, pp. 200. 14 numbers, each 30 

Emerson (H. P.) Latin in High Schools. Paper, 8vo, pp. 9. ... . 25 

Essays on the Kindergarten. Cloth, l2mo, pp. 175 100 

Farnhani (Geo. L.) The Sentence Method of Reading. Cloth, 16mo, pp. 50. 50 

Fitch (Joshua G.) The Art of Questioning. Paper, 12mo, pp. 36 15 

The Art of Securing Attention. Paper, 16mo, pp. 43. Second Edition.. 15 

Lecture* oh Teaching, Ridding Club Edition. Cloth, 12mo, pp. 436, 1 25 

Frcebel (Fr.) Autobiography of. Clotii, 12mo, pp. 183 1 50 

Gill (John.) School Management. 41th Thousand. Cloth, 16mo, pp. 276.... 100 
Granger (Oscar.) Metric Tables and .Problems. Manilla, 16mo, pp. 23 — 25 
Gray (Thos. J.) Methods of Instruction and Courses of Study in Normal 

Schools. Paoer, 8vo, pp. 19 — . — 15 

Griffin (Ida L.) Topical Geography, with Methods and Supplementary Notes. 

Leatherette, 12mo. pp. 142 50 

Hailniann (••-.'. n.) ' Kindergarten Manual. Boards, 8vo, pp. 58 75 

The New Education. 8vo, pp. U6. Two series. ' Each 2 00 

Hall (Marcelia W.) Orthoepy Made Easy. Cloth, 16mo, pp. 100 50 

Harlow (W. B.) Early English Literature. Cloth, 16mo, pp. 138 75 

Harris, (W. T.) Natural Science in the Public Schools. Paper, 16mo,pp. 40. 15 

The Educational Value of Manual Training. Paper, 8vo, pp . 14 15 

Art education The True Industrial Education. Paper, 8vo, pp. 9 15 

Heernians (Forbes.) Stories of the Far West. Cloth, 16mo, pp/280... 1 25 
Hendrick (Mary F.) Questions in Literature. Boards, 12mo, pp v l00... S5 
Hendrick (W.) 41 The Table is Set." A Comedy for Schools, 16mo, pp. SO. . 15 

Hinsdale (B. A.) Pedagogical Choirsin Colleges. Paper, Svo, pp. 11 15 

Hoose (James H.) Studies in Articulation. Cloth, 16mo, pp. 70 50 

On the Province of Methods of Teaching. Cloth, 18mo, pp. 376 1 00 

Pestalozzian First-Tear Arithmetic. Boards, 16mo, pp. 217 50 

Pupils 1 Edifion. Boards, 16mo, pp. 156 35 

*Hornstone Slating, the best crayon surface made. Per gallon 8 09 

Hoss (Geo. H.) Memory Gems. 16mo, paper, pp. 40 15 

Hughes (James L.) Mistakes in Teaching. Cloth, 16mo, pp. 135 50 

How to Secure and Retain Attention. Cloth, 16mo, pp. 98 50 

Huntington (lit. Rev. F. D.) Unconscious Tuition. Paper, 16mo, pp. 45.. 15 

Hutton (H. II.) A Manual of Mensuration. Boards, 12mo, pp. 168 50 

Jackson (E. P) Class Record Cards. 90 white and 10 colored cards 50 

Johnson's Chart of Astronomy. On blue enamelled cloth, 40x46 inches 3 50 

Johnston'? Wall Maps. Send for Circulars. 

♦Jones's i?t>- nble Blackboard Erasers. Per dozen ICO 

Julian d (Anna M.) Brief Views of U. S. History. Leatherette, 16mo,pp. 68. 35 

Keller (C.) Monthly Report Cards. 2Mx4 inches. Per hundred 100 

Kennedy (John.) The Philosophy of School Discipline. 16mo, pp. 23... 15 
Kiddle (Henry.) 8000 Grammar Quests ns, with Full Answers and Refer- 

ences to all leading Text Books. Cloth, 16mo. pp. 220 1 00 

Landon (Jos.) School Management. 12mo, pp. 376 1 25 

Latham (Henry ) On the Action of Examinations, 12mo, pp. 400 1 50 

Lawrence (E. C.) Recreations in Ancient Field*. Cloth, 12mo, pp. 177. .. 100 
Lowrie (R. W.) How to obtain Greatest Benefit from a Book. Paper, Svo, pp.12 25 

Marble (A. P.) Powers of School Officers. Paper. 16mo, pp. 27 15 

»Iarenholz-~Buelow (Baroness) School Work-shops, Paper, 16mo, pp. 27 15 

Child and Child Nature. Contributions to the understanding of FrcebePs 

Educational Theories. Cloth, 12mo, pp. 207 , 150 

Slaudsley (Hj Sex,in Mind and Education. Paper, 16mo, pp. 42 15 



LABOEATOET AIANUAL 



EXPERIMENTAL PHYSICS. 



A BEIEF COURSE OF QUANTITATIVE EXPERIMENTS 
INTENDED FOR BEGINNERS. 



ALBERT L. AREY, C. E., 
Instructor in Physics, Bocliester Free Academy. 



WITH- ILLUSTRATIONS. 



I 




SYRACUSE, B". Y. : 

C. W. BAKDEEN, PUBLISHER. 

1890. 



Copyright, 1890, by C. W. Bardeen. 



PREFACE. 



In preparing these experiments the author's aim 
has been: first, to provide a series of experiments 
suited to the ability of the average student in our 
secondary schools, which would require him to make 
measurements of some kind; second, to devise inex- 
pensive apparatus with which results may be ob- 
tained sufficiently accurate to point conclusively to 
the law under consideration. 

The value of illustrative experiment is not denied, 
but it is claimed that vastly greater mental discipline 
will be derived by the student from quantitative 
experiment, and therefore that it is wiser to confine 
the illustrative experiments to the lecture table, and to 
use the limited time which can be spared for labora- 
tory work on those experiments which will yield the 
richest returns. 

In the first experiment an effort is made to bring 
the student face to face with what may be called his 
personal equation of error, to teach him that intelli- 

Oii) 



gent consideration and careful manipulation are nec- 
essary if accurate results are to be obtained . The 
teacher should endeavor to show him that success 
in these matters is within his reach, and should 
urge him to consider the sources of error in the experi- 
ment before him and to devise means of avoiding them. 
It is suggested that the teacher keep a record of the 
per cent, of error made by each student, in eacrr 
experiment, the average per cent being a sort of per- 
sonal equation for the given pupil. This will vary 
more than, would at first thought, be expected, and 
will assist the teacher materially in his endeavor to 
secure accurate work. 

In addition to the record of numerical work indi- 
cated in the forms for entering results, the student 
should explain fully any mathematical process em- 
ployed in any part of his work, should record the 
arithmetical mean of each series of results, together 
with the error of the largest and the smallest value 
obtained, and should compare his results with those 
given by theory or by other experiments. 

A full description of any departure from the printed 
instructions, or alteration of the apparatus, and a 
statement of any sources of error discovered, with the 
best means of avoiding them, should also be given. 



PREFACE. V 

Many of the experiments of this course are new; 
others are found in all works on Practical Physics, 
I wish, however, to acknowledge especial indebtedness 
to the treatises of Stewart and Gee, of Worthington, 
and to the Harvard Preparatory Physics by Dr. Hall. 
I am also indebted to Mr. J. E. Putnam, late assistant 
in Physics at Michigan University, for valuable sug- 
gestions in connection with Experiment 39 and others. 

Kochester, N. Y., Jariy 25th, 1890. 



CONTENTS. 



PROPERTIES OF MATTER. 
Experiment. Page. 

I. Length 10 

II. " ..12 

III. The Jolly Balance. 14 

IY. An Indirect Measurement 16 

V. Tenacity 18 

VI. Density 20 

VII. Elasticity— Stretching. 22 

VIII. " —Bending ..24 

IX. " " 28 

FLUIDS. 

X. Pascal's Vases 30 

XL Liquid Pressure— Upward... ..34 

XII. " " —Downward. 38 

XIII. " " —Lateral... ...40 

XIV. Barometer— Construction. .49 

XV. " — Measuring heights ..46 

XVI. Boyle's Law ..48 

XVII. Pascal's Law 50 

XVIII. Buoyancy— Floating Bodies 52 

XIX. " — Immersed " ..54 

XX. Specific Gravity— Heavy Solid 56 

XXI. " " —Light " 58 

XXII. " " -Liquid 60 

XXIII. " " — " 60 

DYNAMICS. 

XX IV. Compositon of Forces— Parallel 62 

XXV. " " " — " 65 

XXYI. " " " —The Parallelogram 68 

(vi) 



CONTENTS. Vll 

XXVII. Newton's Second Law 70 

XXVIII. Atwood's Machine 72 

XXIX. Whiting's Experiment .-74 

XXX. Action and Eeaction. 78 

XXXI. The Pendulum-First Law 80 

XXXII. " " —Second Law 82 

XXIII. " " —Parallelogram of forces .84 

XXXIV. Work -.86 

XXXV. The Lever _ 90 

XXXVI. The Pulley .-94 

XXXVII. The Wheel and Axle.. 96 

XXXVIII. The Inclined Plane 96 

HEAT. 

XXXIX. Expansion 98 

XL. Testing a Mercury Thermometer 102 

XLI. Kate of Evaporation .104 

XLII. Thermal Capacity 106 

XLIII. Latent Heat of Water 108 

XLIV. " " " Steam. 110 

XLV. Specific Heat 114 

SOUND. 

XL VI. Vibrating Strings— Length 116 

XLVII. " " —Tension... .120 

XLVIII. " " —Pitch 122 

XLIX. Pitch of a Tuning-Fork 124 

L. Velocity of Sound — Actual ..128 

LI. " " " —Wave Length 132 

LII. Interference of Sound 134 

LIGHT. 

LIII. Photometry 1 36 

LIV. Law of Reflection of Light ..140 

LV. Plane Mirrors _ 142 

LVI. Convex Lens — Focal Length 144 

LVII. " " —Law 148 



Vlll CONTENTS. 

ELECTRICITY AND MAGNETISM. 

LVIII. Lines of Magnetic Force ..152 

LIX. Distribution of Magnetism 154 

LX. Galvanometer-Defection and Current 150 

LXI. Polarization of Cell 100 

LXII. Battery Resistance 162 

LXIII. Methods of Combining Cells ..166 

LXIV. Reduction Factor of a Galvanometer 168 

LXV. Ohms Law— E. M. F._ 170 

LXVI. " " —Fall of Potential 172 

LXVII. Resistancs of Wires— Length . 1 76 

LXVIII. " " " —Diameter 178 

LXIX. Specific Resistance 180 

LXX. Determination of E. M. F... 182 

APPENDICES. 

A. The Mirror Scale 184 

B. The Jolly Balance 184 

C. Atwood's Machine 186 

D. The Wide Board ..187 

E. A Spirit Level 187 

F. Apparatus for Exp. 39 .. 187 

G. Calorimeter 189 

H. To Smoke Paper 189 

I. Mercury Contact 189 

J. Electrical Apparatus 190 

I. Battery 190 

II. Tangent Galvanometer ..191 

III. Sight and Scale ..192 

IV. The Rheocord and Bridge 193 

V. The Commutator 195 

VI. The Spools of Wire 195 

VII. Voltameter 196 

K. The Long-Spring Balance 197 

L. A Duprez Galvanometer 198 

M. Alternate Experiments in Elasticity 199 



EXPERIMENTAL PHYSICS. 



EXPERIMENTAL PHYSICS. 



Experiment I. 
Length. 

Apparatus. — Two meter sticks ; pins. 

Directions. 1. Using one of the meter sticks, 
measure along a crack or other straight line on the 
floor a distance not less than 5 m., driving pins firmly 
at each end. 

2. Measure the same distance again using two meter 
sticks alternately, holding one firmly in place until 
the other is in contact with it end to end. 

How do your results agree ? If the error is more 
than 3 mm., verify your results. 

.3. Determine the length of your pace. 

a. Place one heel in contact with one of the pins, 
walk with natural step to the other, counting and 
recording the number of steps and estimating the 
fraction, if any, in tenths of a step. Repeat three 
times. 

b. Pace the distance three times more making a 
slight effort to lengthen the natural step. 

Determine from your results which is the more 
uniform, your natural step or the lengthened step. 

(10) 



11 



Number of 
between pins, natural steps. len f t t ^ p e s ned 



Length of 
natural step. 



Length of 

lengthened 

steps. 



12 EXPERIMENTAL PHYSICS. 

Record the length of the pace which you conclude to 
use hereafter in both feet and meters. 

4. Pace an unknown distance, reduce to meters and 
verify by measuring it. 



Experiment II. 

Apparatus. — A meter stick ; one foot rule ; two 
rectangular blocks 1x2x5 cm.; the mirror scale (see 
appendix 5. 

Directions. 1. Note the length of 10 cm. on the 
meter stick, make two dots on the opposite page 10 
cm. apart estimating by the eye, verify your result. 

2. Repeat the above for 1 cm., 6 inches and 1 inch. 

3. Measure the diameter of some round object as a 
lead pencil or a marble, using the meter stick and 
two rectangular blocks as in Fig. 1. 



Fig. 1. 

4. Measure the diameter of some round object using 
the mirror scale as directed in appendix A. 



EXPERIMENT II. 13 



14 EXPERIMENTAL PHYSICS. 

Experiment III. 

The Jolly Balance. 

To determine the value of one division of the pro- 
file jjaper in grams. 
Apparatus. — The spring balance described in ap- 
pendix B ; a set of weights from 10 to 50 g. 

Directions. 1. With the smaller spring in place 
adjust the index to zero. 

2. Place 10 g. in the scale u3££BBM 
pan, read and record the posi- | 
tion of the index. H 

3. Repeat using 20, 30, 40 
and 50 g. 

4. Determine the number 
of divisions which the spring 
has been lengthened by 1 gram 
in each case and take the re- 
ciprocal of the average of -*s . 
these values as the modulus ^J^-^JIll 
to be used in reducing the Fig. 2. 
scale reading to grams. 

The modulus should be written on a small piece of 
card board and attached to the upper hook of the 
spring. 

5. Repeat the experiment with the large spring. 



the jolly balance. 
Small Spuing. 



15 



Weight. 


Reading. 


Elongation per gram. 


10 g. 
20 g. 
30 g. 
50 g. 









Larue Spring. 


Weight. 


Reading. Elongation per gram. 


10 g. 






20 g. 






30 g. 






50 g. 







16 EXPERIMENTAL PHYSICS. 

Experiment IV. 

An Indirect Measurement. 

Apparatus. — The Jolly balance ; a piece of small 
bare copper wire ; thread ; a dish of water ; a meter 
stick. 

Directions. 1. Measure the length of wire. 

2. Weigh the wire in air, then suspend it by a 
thread and weigh it in water. 

3. Keduce the weights just found to grams by mul- 
tiplying the reading by the modulus of the spring 
used. 

4. Find the loss of weight in water in grams ; this 
will be numerically equal to the volume of the wire in 
ccs. from which the diameter may be computed by 
the following formula. 

Diameter=1.128 t/ volume 
r length 

Optional. — Derive the above formula. 



AN INDIRECT MEASUREMENT. 



17 



18 EXPERIMENTAL PHYSICS. 

Experiment V. 
Tenacity. 

Apparatus. — A 24 lb. spring balance; 1 in. of No. 
27 spring brass wire. Also two stirrups made 
as follows: saw a piece 8 cm. long from a broom- 
stick, bore a small hole 1 cm. from each end, 
bend 30 cm. of No. 16 copper wire in the mid- 
dle, so as to form a letter U. Insert the ends of 
the wire in the holes of the wood, twist the 
free ends around the stick and fasten them 
there, thus forming a short stirrup. 

Directions. 1. Wind one end of the wire 
to be broken three or four times around the 
wood of one of the stirrups, and hanging the 
stirrup over a stout nail twist the same end of 
the wire around the nail. In the same manner 
attach the other end of the wire to the remain- 
ing stirrup, hanging it over the hook of the 
spring balance instead of a nail. 

2. Pull steadily with the balance, watching 
the index and noting the force required to break 
the wire. 

3. Repeat the experiment three times. The 
same wire will generally answer. Fig. 3. 

4. Break in the same manner wires of iron and of 
German silver. 

Be careful to grasp the balance in such manner 
that the hook cannot strike the hands when it recoils. 



TENACITY. 



19 



Kind of wire. 


Size. 


Breaking strain. 






S 



20 EXPERIMENTAL PHYSICS. 

Experiment VI. 

Density, 

Apparatus. — A rectangular-sided block of wood, 
glass, or hard rubber, containing 30 or 40 cc ; the 
Jolly balance; a meter stick ; a foot rule ; a small 
piece of iron or brass; a vessel graduated to cu. cms. 

PART I. 

Directions. 1. Measure the sides of the block 
and compute its volume in ccs. : small fractions must 
not be neglected. 

2. Weigh the block and compute its weight in 
grams per cubic centimeter. 

PART II. 

1. Weigh the iron. 

2. Partly fill the graduated vessel with water, note 
the volume of water used, reading the bottom of the 
meniscus ; immerse the iron, and observe the volume 
of water again, the difference will be the volume of 
the iron. 

3. Determine the density as before. 



ELASTICITY. 21 



22 EXPERIMENTAL PHYSICS. 

Experiment VII. 
Elasticity. 

Stretching. 

Apparatus. — A strip of pure rubber 2 cm. wide, 
1 mm. thick, and 65 cm. long ; two pieces of wood 
1x2x5 cm.; a meter stick; some strong twine and 
small tacks; a set of weights from 10 to 500 g. 

Directions. 1. Using at least three tacks, 
fasten one end of the strip of rubber to one of 
the pieces of wood. To the same face of the 
block tack a short loop of twine. 

2. In the same manner fasten the other end 
of the rubber to the other block of wood. Make 
marks with ink about 50 cm. apart on the rub- 
ber. 

3. Measure the elongation produced by- 
weights of 10, 20, 30, 50, 100, 500 g., until the 
strip does not resume its original length when 
the weight is removed. 

4. Record your results in the proper place on 
the opposite page, and state the relation which 
exists between the weight and the elongation 
it produces. 

Note. — An initial load of about 50 g. should be at- 
tached to straighten the rubber and this weight should not 
"be considered in subsequent operations. Fig. 4. 



ELASTICITY. 



23 



No. 


Weight. 


Length of Strip 
between Marks. 


Elongation Total. 


Elongation 
per Gram. 


1 



10 g. 






' 


2 



20 g. 








3 



30 g. 








4 




50 g. 








5 



100 g. 








6 



500 g. 









24 EXPERIMENTAL PHYSICS. 

Experiment VIII. 
Elasticity. 

Bending. 

Apparatus. — A box of weights from 100 to 500 g. ; 
a meter stick; two blocks of wood 2x5x5 cm. Make a 
saw cut across each block about 5 mm. deep and into 
these slip pieces of sheet metal about 2 mm. thick 
and 1 cm. wide so that the upper edges of the strips 
of metal may serve as knife edge supports for the 
laths. 

Bend a piece of copper wire as in Fig. 6 making 
the ends of equal weight and 2 cm. long, place the 
wire on a piece of iron and flatten the loop with a 
hammer so that the ends of the wire shall lie in the 
same plane, fasten this wire to a block of wood by 
means of a ivire nail; slip a piece of straw over the 
straight end of the wire and fasten it in place with 
sealing wax; attach a short bit of bristle to the free 
end of the straw making the long arm of the lever 
thus formed about 25 cm. long. 




Fig. 5. 
Tack a piece of profile paper to a block of wood in- 
clining it about 5° from a perpendicular, the object 



ELASTICITY. 



25 



Load 


lD ?. ex 1 Deflection 
readings. L»er*ecuon. 


Increase for 
100 g. 



100 g. 


200 g. 


300 g. 


400 g. 


500 g. 









26 



EXPERIMENTAL PHYSICS. 



being to provide a 
scale which shall indi- 
cate the position of 
the lever with ac- 
curacy. 




Ftg. 0. 



Directions. 1. Arrange the apparatus as shown 
in Fig. 5, the supports being 90 cm. apart, and the 
lever exactly in the centre. 

2. Determine the deflection of the lath produced 
by loads of 100, 200, 300, 400 and 500 g. respectively 
applied at the centre. 

3. What law connects the deflection with the 
weight producing it. 

Note. — Record the zero reading before applying a load and 
see whether the index conies back to the same position when the 
load is removed. Throw out any load which is thus shown to 
exceed the limit of elasticity. 



ELASTICITY. 27 



28 EXPERIMENTAL PHYSICS. 

Experiment IX. 
Elasticity. 

Bending. 
Apparatus. — The same as Exp. 8. 

Directions. 1. Determine the deflections pro- 
duced by 500 g. when the supports are 80, 60, and 
40 cm. apart. 

2. Repeat the above measurements using a load of 
1000 g. 

Do you discover any important relation between the 
length of the lath and the deflection ? 

Note — The relation does not always appear to the student on 
inspection of the results. If he is directed to deduce the deflec- 
tion made by the shortest lath from that made by the longest, by 
proportion, he will at once decide to which of the three columns 
the deflection is proportional. 



ELASTICITY. 



29 



Length. 


Square of length. 


Cube of length. 


Deflection. 











30 



EXPERIMENTAL PHYSICS. 



Experiment X. 
Liquid Pressure. 

Relation between pressure and quantity of liquid. 

Apparatus. — Two vessels made of thin sheet brass 
of equal height, one conical, the other cylindrical, 
each having a cast brass rim at the bottom in which 
the brass ring shown in Fig. 8 may be secured; a 
retort stand; a lever and profile paper scale (see Exp. 
8) ; a float made as follows : fasten a piece of straw 
15 cm. long to one end of a cork 15 mm. in diameter 
and 15 mm. long. Screw a one-inch screw in the 
other end to give it stability. Place the float in a 
cup of water and make ink marks on the straw at 
points 5, 10 and 15 cm. above the surface of the water. 
A piece of very thin sheet rubber 15 cm. square. 





Fig. 7. Fig. 8. 

Directions. 1. Tie the sheet rubber on the ring 
(Fig. 8) with linen thread and attach it to the coni- 



LIQUID PRESSURE. 31 



32 EXPERIMENTAL PHYSICS. 

cal vessel which we shall hereafter designate as ves- 
sel No. 1. Arrange the apparatus as shown in Fig. 7. 

2. Record the leading of the lever with the vessel 
empty. Fill the vessel with water to a point 15 cm. 
below the top, as indicated by the float, and record 
the lever reading. In like manner take readings 
when water level is 10 and 5 cm. below the top and 
also when the vessel is full. 

3. Attach the brass ring and rubber to vessel No. 
2, and take lever readings at the same points as above. 
Fill out the table on the opposite page and write 
answers to the following questions. 

What relation exists between the shape of the ves- 
sel and the pressure ? between the quantity of water 
and the pressure ? 

Optional. — Does the deflection of a rubber di&k 
supported at the edges bear the same relation to the 
load that the elongation of a strip of rubber does ? 
(see Exp. 7.) 



LIQUID PRESSURE. 



33 



Depth. 


Readings. 


Deflection . 


Deflection 
per cm. 


No.l. 


No. 2. 


No. 1. 


No. 2. 


No.l. 


No. 2. 

















34 



EXPERIMENTAL PHYSICS. 



Experiment XI. 
Liquid Pressure. 

Relation between Upward Pressure and Depth. 

Apparatus. — A glass tube about 5 mm. internal 
diameter bent as in Fig. 9, the long arm being 25 cm. 
long A cylindrical glass vessel containing water. 
A cork to fit the vessel, perforated near one side to 
receive the bent tube. A mirror scale; mercury; and 
a small glass funnel with rubber connector. 

Directions. 1. See that 
the tube is perfectly dry, 
pour a small amount of clean 
mercury into it and adjust 
in the vessel. 

2. Place the vessel before 
the mirror scale in such po- 
sition that the image of the 
tube may be seen at one 
side of the vessel, if seen Iff 
through it the position of 
the image may be dis- *Fte! 9. 

placed by irregularities of the glass and inaccurate re- 
sults may be obtained. The best position is easily 
found by turning the vessel around until the image 
of the tube appears on the scale and is partly covered 
by the tube itself. 

Read the position of the bottom of the meniscus of 
the water which rises in the tube and the surface of 




LIQUID PRESSURE. 35 



36 EXPERIMENTAL PHYSICS. 

water in the vessel, adjust the tube so that the differ- 
ence in the readings is 5 cm. 

3. Tf care be taken not to allow the tube to 
change its depth, the vessel may now be moved to 
bring the images of the mercury columns in proper 
position for reading with the least possible change 
of position between the readings. Read the position 
of the top of the meniscus in each arm and carry 
out the difference between them as the elevation of 
the mercury. 

4. Repeat the operation for depths of 10, 15, and 
20 cm. 

5. Write the relation between upward pressure 
and depth. 

Note. — If not convenient to use " cylinders " for this experi- 
ment, 6x8 battery jars may be substituted in which case the tube 
may be supported by a "spider" such as is frequently used to 
support the zinc in a gravity battery. 

Carbon bisulphide colored with iodine will be found more 
satisfactory than mercury for experiments in liquid pressure. 



LIQUID PRESSURE 



37 



Depth. 


Readings. 


Elevation of 
mercury. 


Elevation 
per cm. 


Short. 


Long. 













38 EXPERIMENTAL PHYSICS. 

Experiment XII. 
Liquid Pressure. 

Relation between Downward Pressure and Depth. 

Apparatus. — Mirror scale; retort stand; cork; a U 
shaped tube, 5 mm. internal diameter, the arms being 
35 and 40 cm. long respectively; mercury. 

Directions. 1. Pour Wi\ 

mercury into the tube i 

until the columns are 
about 5 cm. high . Then j 

pour in about 10 cm. of jj 

water. 

2. Support the tube be- ll' Wilt* 
fore the mirror scale as ■'■; \J\ 
shown in figure 10, and BUgJ 
read the upper and lower ^f y* 
surfaces of the water and — ™==dtE3SB-Bp f 
the elevation of the mer- Fig. 10. 

cury in the other arm. Fill out the blank on the op- 
posite page computing the elevation per centimeter of 
depth. 

3. Kepeat the above making the depth of water 15, 
20 and 25 cm. respectively. 

4. What relation between downward pressure and 
depth is shown ? 

N. B. — Suspend the tube in such position that all readings for 
the given depth may be taken without moving it. 



LIQUID PRESSURE. 



39 



Upper 
surface 
of water. 


Lower 
surface 
of water. 


Mercury. 


Depth 
water. 


Elevation 
mercury. 


Elevation 
per cm. 















40 



EXPERIMENTAL PHYSICS. 

Experiment XIII. 



Liquid Pressure. 

Relation between Lateral Pressure and Depth. 

Apparatus. — A mirror scale; mercury; a bottle 
to catch the overflow; and the following instrument : 
Obtain from a plumbsr a piece of 1^-inch gas pipe 15 
inches long with cap on one end. Near the top have 
a piece of i-inch gas pipe about two inches long in- 
serted to serve as an overflow pipe. Measuring from 
lower edge of the hole in the overflow pipe drill f- 
inch holes 10 cm. apart and pro- 
vide corks to fit them. Bend a 
piece of glass tubing about 3 
mm. internal diameter to the 
form shown in the cut, the short 
arm being 5 cm. long, fit a per- 
forated cork on the horizontal 
position. 

Directions. — 1. Insert the 
bent tube in the 10 cm. hole; fill 
it nearly to the horizontal arm 
with mercury ; place the bottle Fig. 11. 

in proper position to catch the overflow and fill the 
pipe with water. Arrange the mirror scale as shown 
in Fig. 11. 

2. Determine the elevation of the mercury for 
depths of 10, 20, and 30 cm., recording your results 
in the proper place. 




LIQUID PKESSURE. 



41 





Deutb. 


Readings. 


Elevation per em. 


* 


Short Arm 


Long Arm. 















42 



EXPERIMENTAL PHYSICS. 



3. What relation do you discover between lateral 
pressure and depth ? Between the upward, down- 
ward and lateral pressure at the same depth ? What 
influence has the smaller diameter of the tube used 
in Exp. 13 on the results ? How may the relative 
density of mercury and the water used be obtained 
from the results of these experiments ? 

Experiment XIV. 

Barometer, 

Apparatus. — A frame 1 m. 
high (see Fig. 12); a piece of 
barometer tubing 80 cm. long 
closed at one end; a yard- stick 
fastened to the frame by clamps 
made of spring brass (see Fig. 
12 A) ; a vessel containing clear 
mercury. 

Directions. 1. Bore holes 
through the frame in proper 
places to receive the wire or 
twine which is to attach the 
tube to the frame, provide pieces 
of wire or twine and have them 
ready for use when required. 

2. Make a small paper funnel s ' 
and pour mercury through it into 
the tube until it is nearly full. 

3. Cover the open end with the 




BAROMETER. 43 



44 EXPERIMENTAL PHYSICS. 

thumb or finger and invert the tube once or twice 
thus allowing a larger air bubble to pass through the 
mercury to gather up any smaller air bubbles which 
may have adhered to the tube; when these are re- 
moved, fill up to the top, close the open end as before 
and invert the tube in the vessel of mercury : remove 
the finger and the mercury in the tube will descend 
to a certain height above the level of that in the vessel. 
Measure this height. 

4. Incline the tube until the mercury nearly reaches 
the end and again measure the height of the mercury 
column. Explain. Compare the reading of your 
barometer with that of the standard barometer in the 
laboratory. 

5. Tie the tube in place and, if possible make a 
record of the height of the column measured at a cer- 
tain hour every day for a week. 

Note. — A yard-stick minus the brass end pieces should be 
used and should be adjusted so that the lower end is in contact 
with the surface of the mercury in the vessel. 



BAROMETER. 45 



46 EXPERIMENTAL PHYSICS. 

Experiment XV. 
Barometer. 

Measuring Heights. 
Apparatus. — An aneroid barometer. 

Directions. 1. Observe the reading of the barom- 
eter on the ground floor of the school building. Carry 
it without delay to the upper floor and read the pres- 
sure indicated there. 

2. Ascertain the actual difference of elevation by 
measurement and compare it with the result obtained 
by allowing 87 feet for each tenth of an inch fall of 
the barometer. 



BAROMETER. 



47 



48 EXPERIMENTAL PHYSICS. 

Experiment XVI. 

Boyle's Law. 

Apparatus. — A piece of barometer tubing lim. 
long; a meter stick; mercury; retort stand; spirit 
level; 5 cm. of rubber tubing; a glass funnel. 

Directions. 1. Close one end of the barometer 
tube making the end as nearly flat as possible. Bend 
the tube about 20 or 30 cm. from the closed end form- 
a U with one arm much longer than the other. 

2. Remove the rings from the retort stand and tie 
the long arm of the tube firmly to the upright, level 
the base plate. Attach the funnel to the open end 
of the glass tube with the rubber tubing. 

3. Pour mercury into the tube until the column in 
the long arm is slightly higher than that in the short 
arm. Measure the distance from the base plate to 
the top of each column of mercury and to the top of 
the short arm of the tube, recording these distances in 
the proper place. 

4. Add 10 or 20 cm. of mercury and read again, 
repeating the process until the long tube is full. 

Note.— The volume is obtained by subtracting the height of 
the mercury in the short arm from the height of the top of the arm. 



boyle's law. 



49 



. Short Long j) ifferen0P Height of Sum = Vol- 
°- arm. arm. - uinerence - Barometer . total pres. ume. 



Product 
vol. X pres. 



50 



EXPERIMENTAL PHYSICS. 



Experiment XVII. 
Transmission of Pressure. 

Apparatus. — An Argand gas burner chimney ; a 
cork or rubber stopper to fit it ; 30 cm. of glass tub- 
ing about 1 cm. internal diameter ; 2 strips of wood 
2x2x15 cm.; a retort stand ; a mirror scale. 

The construction of the apparatus 
is clearly shown in Fig. 13. It is 
held in place on the retort stand by 
short pieces of brass which cover 
grooves cut in the strips of wood. 




Directions. 1. Pour enough mer- 
cury into the large tube to cover the 
bottom 4 or 5 mm. deep. Place the 
mirror scale in a convenient position 
and read the elevation of the surfaces 
of the mercury in the tubes.* 

2. Pour about 100 cc. of water in Fiu. 13. 

the large tube and watching the elevation of the mer- 
cury in the small tube pour water into it until the 
mercury returns to its former position showing the 
mercury in the two tubes to be on the same level. 

3. Compute the area of each tube, and the weight 
of water in it, recording the quantities in the proper 
column. 

4. Pour more water into the large tube, repeating 
the experiment. 

* If the bent tube used is small enough to affect the level of the mercury 
by capillary action pour enough carbon bisulphide colored with iodine into 
the large tube to bring the surfaces of the mercury to the same level. 



TEANSMISSION OF PRESSURE. 



51 



Exp. 

1 
2 



Large. Small. 



Large Small 



Ratio of weights. 



Ratio of areas. 



52 EXPERIMENTAL PHYSICS. 

5. State the relation between the pressure applied 
to the mercury in the small tube and the weight sup- 
ported in the large tube. 

Experiment XVIII. 
Buoyancy. 

Floating Bodies. 

Apparatus. — A graduated cylinder reading to 
cubic centimeters ; a six-inch test tube ; the Jolly 
balance ; 5, 10, and 20 g. weights. 

Directions. 1. Fill the cylinder about two- 
thirds full of water, record the amount, float the test 
tube, open end up, in the water and record the in- 
creased volume. 

2. Place a 5 g. weight in the test tube, observing 
the new volume. 

3. Kepeat, using 10, 15, and 20 g. weights. 

4. Now weigh the test tube and fill out the table 
on the opposite page. 

5. Write as a law the relation which exists between 
the weight of a floating body and the weight of the 
water displaced. 



BUOYANCY. 



53 



Weight of 
test tube. 



Added 
weight. 



Original 

volume of 

water. 



Increased 
volume. 



Weight of . 

water ~ 
displaced. 



54 EXPERIMENTAL PHYSICS. 

Experiment XIX. 
Buoyancy. 

Immersed Bodies. 

Apparatus. — A graduated cylinder ; the Jolly 
balance ; a mirror scale ; a vessel of water ; several 
substances heavier than water. 

Directions. Suspend one the substances from the 
hook of the Jolly balance by means of a thread ; de- 
termine the weight in air ; weigh it again with the 
substance immersed in water ; reduce these weights 
to grams and record them, carrying out the loss of 
weight in water. 

2. Partly fill the cylinder with water, adjust the 
level to some one of the divisions of the scale with a 
pipette, record this as the original volume and drop 
the substance just weighed into the cylinder, read 
the increased volume* and compute the weight of 
water displaced. 

3. Kepeat the operation with as many other sub- 
stances as time will permit. 

4. Compare the weight lost by each substance with 
the weight of water displaced. 



* If the cylinder used is graduated to cubic centimeters satisfactory re- 
sults may be obtained by estimating fractions of a cu. cm., but in oase the 
marks on the scale are 5 cu. cm. apart, it will be necessary to interpolate 
the reading as follows— place the cylinder on the base of the mirror scale, 
read the elevation of (a) the division below the surface of the water, (b) 
the water surface, (c) the mark above the water, and computing the frac- 
tion of a division by simple proportion. 



BUOYANCY. 



55 



Sub- 
stance. 



Wt. 
in air. 



Wt. in 
water. 



Original 
volume. 



Increased 
volume, 



Weight of wa- 
ter displaced. 



56 EXPERIMENTAL PHYSICS. 

Experiment XX. 
Specific Gravity. 

Solids heavier than water. 

Apparatus. — The Jolly balance ; a beaker of 
water ; thread ; pieces of iron, brass, lead, glass, etc., 
weighing less than 50 g. 

Directions. 1. With the large spring in place, 
attach a suitable length of thread to the hook and ad- 
just the index to the zero of the scale. Make a slip- 
knot in the end of the thread and attach one of the 
substances to be examined. 

2. Weigh in air, and then in water and tabulate 
your results on the opposite page. 

3. Repeat, using the other substances. 

4. Find the volume in cu. cm., by multiplying the 
loss of weight by the modulus of the spring. 



SPECIFIC GRAVITY. 



57 



Substance. 


Reading of balance. 


Loss. 


Specific gravity 


Volume. 


Air. 


Water. 















58 EXPERIMENTAL PHYSICS. 

Experiment XXI. 
Specific Gravity. 

Solids lighter than water. 

Apparatus. — The Jolly balance ; a smooth-sided 
block of wood containing 5 or 10 cu. cms.; a piece of 
sheet lead heavy enough to sink it. 

Directions. 1. Weigh the wood in air. 

2. Bend the sheet lead around the wood and weigh 
the combined mass in water. 

3. Find the loss of weight of the lead alone and 
calculate the specific gravity of the wood. 

4. Repeat, using other light substances. 
Optional. 

Can the specific gravity of a light solid be obtained 
without weighiug the sinker in air ? 



SPECIFIC GRAVITY. 



59 



Substance. 


Weight 
in air. 


Weight in water. 


Loss. 


Specific grav. 


Combined 
mass. 


Sinker. 















60 EXPERIMENTAL PHYSICS. 

Experiment XXII. 
Specific Gravity. 

Liquids — Bottle Method. 

Apparatus. — The Jolly balance ; a one-ounce 
glass-stoppered bottle ; a cloth ; water ; kerosene 
oil ; glycerine ; brine, etc. 

Directions. 1. Weigh the bottle and stopper, 
fill with water, dry with the cloth and weigh again. 

2. Weigh the same bottle filled with oil and com- 
pute the specific gravity. 

3. Repeat, using other liquids. 



Experiment XXIII. 
Specific Gravity. 

Liquids — Bulb Method. 

Apparatus. — The Jolly balance ; a glass stopper 
or a lead bullet ; water ; other liquids. 

Directions. 1. Weigh the bullet in air, then in 
water, then in the other liquids. 
2. Compute the Specific gravities. 



SPECIFIC GRAVITY. 



61 



Liquid 
examined. 


Weights. 


Specific 
gravity. 


Bottle. 


Bottle 4- 
water. 


Water. 


Bottle 4 
liquid. 


Liquid. 

















Liquid 
examined. 


Weight of bullet in 


Specfie gravity. 


Air. Water. 


Liquid. 










> 



62 EXPERIMENTAL PHYSICS. 

Experiment XXIV. 
Parallel Forces. 

To determine the magnitude and point of appli- 
cation of the resultant . 

Apparatus. — A wooden bar 2x3x110 cm ; two 24- 
1b. spring balances ; two screw eyes ; two retort 
stands ; a known weight (sash weights will be found 
convenient and economical for this and many other 
experiments). 




Fig. 14. 

Directions. 1. Insert the screw eyes in the edge 
of the bar just 1 m. apart, draw pencil lines on the 
bar 10 cm. apart and arrange the apparatus as shown 
in Fig. 14. 

2. Before attaching the weight read and record the 
allowance for the weight of the bar. Call this the zero 
reading and subtract it from all subsequent readings 
of the given balance to obtain the corrected reading. 

3. Using a loop of strong twine, suspend the weight 
10 cm. from one of the screw eyes, record the weights 



PARALLEL FORCES. 



63 



Balance 
readings. 


Corrected 
readings. 


Sum. 


Distances. 


Products. 


Right. 


Left. 


Right. | Left. 


Right. 


Left. 


Right. 


Left. 





















64 EXPERIMENTAL PHYSICS. 

indicated by the balances, and fill out the table on 
page 63. 

4. Repeat the experiment at intervals of 10 cm. 
throughout the length of the bar. 

5. Write your own conclusions concerning the rela- 
tions between the magnitude of the resultant and the 
sum of the component forces. Also the relation be- 
tween the magnitude of the component forces and the 
point of application of the resultant. 

Experiment XXV. 
Parallel Forces. 

Center of Gravity. 

Apparatus. — A bar of f-inch iron about 1 m. 
long, of known weight ; a three-cornered file ; a set 
of weights from 500 g. to 2000 g. ; a meter-stick. 

Directions. 1. Solder a brass ear to one end of 
the bar of iron, place the file near one end of the 
table and balance the bar carefully upon it. When 
it is exactly in equilibrium grasp the bar with one 
hand each side of the file and move it a short dis- 
tance, pressing with sufficient force to mark distinctly 
on the iron, the position of the cross-section in which 
the center of gravity lies. 

2. Suspend the 500 g. weight from the ear and bal- 
ance the bar, making a file-mark as before. Measure 
the distance between this mark and the ear and 
record the product of this distance and the weight 



PAKALLEL FORCES. 65 



66 EXPERIMENTAL PHYSICS. 

in the column headed " moment." Considering the 
weight of the bar (which must be known within 1 
g.) as one downward force, the 500 g. weight as 
the other, apply the teachings of the last experiment 
and find how far the weight of bar must be applied in 
order to balance the 500 g. Enter this distance un- 
der u Computed arm" and measure the distance 
between the center of gravity and the file-mark just 
made as the " Actual arm." 

3. Repeat the experiment, using 1000, 1500,2000, 
and 2500 g. respectively. 

Have the forces of gravity of all the molecules acted 
in each of the above cases as though they were a 
single force having a definite position in the bar ? 

4. Optional. — Suspend 2000 g. from the ear and 
500 g. from the other end of the bar, balance it on the 
file and account for the position of equilibrium. Why 
does it not balance with the fulcrum \ the length 
from the 2000 g. weight ? 



PARALLEL FORCES. 



67 



WPiVht Arm Product or Weight Comput- Actual F _ 

Weignt. Aim. n,.,,,^ nfhn.r pd arm arm & 1 



ed arm. arm, 



68 



EXPERIMENTAL PHYSICS. 



Experiment XXVI. 
Composition of Forces. 

The Parallelogram. 

Apparatus. — The wide board (see Appendix D) ; 
a sheet of foolscap paper and four thumbtacks ; a 
block of wood about 10x10x20 cm. ; 2 wooden pegs ; 
2 pulleys ; weights ; stout twine ; a small iron ring. 

Directions. 1. Suspend one pul- 
ley from a peg in one of the side holes 
and the other from one of the top 
holes. Pass a piece of twine over one 
of these pulleys, then through the 
Iron ring, then over the other pulley. 
Tie small wire hooks to each end of 
the twine and a third one to a shorter 
piece which is attached to the iron = 
ring. 

2. Suspend known weights from 
each of the hooks, observe that as 
either of the weights is changed the 
position of one or more of the cords is - 
altered. Fasten the paper to the 
board as in Fig. 15. 

3. Using the block of wood as a guide, draw pen- 
cil lines on the paper, parallel to and behind AC and 
AB. 

4. Prolong these lines to their intersection and 
from this point lay off on each line as many units of 



Fig. 15. 



COMPOSITION OF FORCES. 69 



70 EXPERIMENTAL PHYSICS. 

length as there are units of weight attached to it. 

5. Complete the parallelogram and compare the 
force represented by the diagonal with the middle 
weight attached to the iron ring. 

6. Reproduce your drawing on a smaller scale on 
the next page ; repeat, varying the weights and the 
position of the pegs. 

Experiment XXVII. 
Newton's Second Law. 

The effect of an Accelerated Force upon a body 
already in motion. 

Note. — This experiment is so simple and witbal so satisfac- 
factory that the author has inserted it nearly as it was originally 
given in the Harvard Preparatory Physics. 

Apparatus. — A T formed by fastening a piece of 
wood about 1x3x10 cm. across the end of a stick 
about 1x3x50 cm ; 2 small marbles ; a level. 

Directions. 1. Cut a rectangular-sided block 
from the upper corner of each end of the cross-piece, 
just large enough to allow a marble to rest in each of 
the niches so formed. Fasten the free end of the 
stem of the T to the top of the wide board with a 
screw, making both arms horizontal. 

2. Place a marble in each niche and strike the T 
near the cross-piece with a ruler, and determine 
whether the marbles thus dislodged strike the floor 
at the same instant. 



newton's second law. 71 



72 EXPERIMENTAL PHYSICS. 

Experiment XXVIII. 

Accelerating Action of a Constant Force. 

Apparatus. — An Atwood's Machine*; a battery j 
a meter-stick ; a pendulum, beating seconds or half 
seconds, arranged to make and break the battery cur- 
rent at the center of each swing. This can be done 
by placing a globule of mercury in a cavity cut in a 
block of wood and placing it so that a piece of wire 
attached to the bottom of the pendulum bob will 
touch the globule when the pendulum is at rest. 

Directions. 1. Using a light overweight in its 
proper place, determine the distance which the weight 
descends in one second, also the velocity acquired in the 
same time — record your result on the opposite page, 
and displacing the shelves repeat the experiment. 

2. Make similar determinations for 2 and 3 seconds. 

3. Repeat the above exercises using a heavier over- 
weight. 

4. State your conclusions concerning : — 

(a) The relation between the time and the final 
velocity. 

(b) The relation between the time and total dis- 
tance. 

(c) The relation between the time and the distance 
moved during the last second. 

(d) Any obvious fact concerning the acceleration. 

* Directions for making an excellent Atwood's Machine will be found 
In Appendix B. 



ACCELERATING ACTION. 
LIGHT OVERWEIGHT. 



73 



Time. 


Final 

velocity. 


Distance. 


Acceleration. 


Total. j Last second. 













HEAVY OVERWEIGHT. 



74 



EXPERIMENTAL PHYSICS. 



Experiment XXIX. 
Gravity. 

Whiting's Experiment. 

Apparatus. — Two one-ounce lead bullets ; 1£ m. 
of fine wire ; cotton thread ; two wooden pegs about 
15 mm. in diameter ; the wide board ; two wire 
nails ; matches ; a meter-stick. 

Directions. 1. At about the 
height of the eye, bore two holes 
in the wide board, one above the 
other, to receive the wooden pegs. 
Cut off the lower one so that it 
will project about 3 cm. Attach 
the wire to one of the bullets A 
and wind the free end around the 
upper peg. Split the end of the 
lower peg and insert the wire in it. 
The pendulum thus formed may 
"be lengthened or shortened by turn- 
ing the upper peg. Adjust it so 
that it is about 1 m. long, remem- 
bering that the " center of suspen- 
sion 



Fig. 16. 
is the lower edge of the lower peg. 

2. Attach the thread to the second bullet B, and 
holding it by thread so that it just touches the bullet 
at a, drive a wire nail into the board close to the 
thread and about 25 cm. above the lower peg. A 
second wire nail is driven into the board near|the edge, 



75 



76 EXPERIMENTAL PHYSICS. 

as shown in Fig. 16. The bullet B is now raised 
nearly to the first nail, and the thread carried over 
the second nail to the bullet A which is thereby 
drawn aside about 20°. 

3. Burn the thread between the two nails. This 
will release the two bullets at the same instant. Vary 
the length of the pendulum slightly until the two 
bullets strike as they pass. Measure and record the 
distance bullet B falls, if great accuracy is desired, 
bullet A should be coated with lampblack, thus show- 
ing the relative positions of the bullets at the instant 
of impact. 

4. Determine the time of vibration of the pendu- 
lum by counting the vibrations that it makes in a 
minute. Record in the table on the opposite page, 
the distance which bullet No. 2 fell and the time oc- 
cupied in so doing (one-half vibration of the pend- 
ulum). 

5. Shorten the pendulum to I m. and in a similar 
manner determine the distance fallen in \ second. 

6. Write the relation between the time and the 
distance a body falls. 



GRAVITY. 77 



78 EXPERIMENTAL PHYSICS. 

Experiment XXX. 
Action and Reaction. 

Apparatus. — Two unequal known 
weights; cotton thread; wire nails; 
mirror scale; two clamps; the board 
used in Exp. 9; a spirit level; a 
spiral spring made of No. 22 wire, 
the ends being bent into hooks. 

Directions. 1. Suspend the 
weight from the wire nails driven in 
the upper part of the board, with 
threads of about equal length. Us- 
ing the spirit level see that the 
parts of the nails to which the thread 
is attached are in the same hori- 
zontal line. 

2. Clamp the mirror scale to the Fig. 17. 
board about 1 m. below the points of suspension. 
Make the lower edge of the scale etched on the mir- 
ror exactly horizontal. 

3. When the weights come to rest, read the point 
where the thread crosses the line just made horizon- 
tal. Attach the end of the spring to each thread, the 
points of attachment being exactly on the same level 
as the lower edge of the etched scale as shown by re- 
flection. Bead the new positions of the threads. 

4. Compare the deflections produced and the 
weights of the balls and write your conclusions con- 
cerning the forces acting on the two balls. 




ACTION AND KEACTION. 



79 



Weight 
of ball. 


Eeadings. 


Deflection. 


Products . 


Error. 


At rest. 


Spring attach'd 















80 EXPERIMENTAL PHYSICS. 

5. Repeat the experiment using other weights. 

6. Optional. Screw a small pulley into the 

the Jolly balance and by means of a thread with ; 
loop in the end draw each ball aside making the sam 
deflection which the spring caused. Record the force 
required to do this as shown by the weight indicate 

Experiment XXXI. 
The Pendulum. 

The First Law. 

Apparatus.— Weights (small canvas bags fillec 
with sand will answer); linen thread— wax; a meter 
stick; a watch; the wide board. 

Directions. 1. Suspend a weight from a peg in on< 
of the holes in the wide board by means of a waxec 
linen thread about 2 m. long. 

2. Place the meter-stick below it, and, watch ir 
hand, draw the weight aside so that the pendulun 
will describe an arc 25 cm. long. Release the pendu 
lum, counting the vibrations made in one minute. 

3. Repeat making the arc 50 cm. long. 1 m, 
long. Record your results in the proper place ;m< 
write your conclusion concerning the effect of tie 
length of the arc upon the time of vibration. 

4. Now determine the number of vibrations made 
by the same pendulum when the arc is 3 m. long. 



THE PENDULUM. 



81 



Length of arc. 



No. of vibrations. 



82 EXPERIMENTAL PHYSICS. 

Experiment XXXII. 
The Pendulum. 

The Second Law. 
Apparatus. — The same as in Exp. 31. 

Directions. 1. In the second form record the 
length and number of vibrations of the pendulum used 
in Exp. 31. 

2. Suspend another pendulum from the same sup- 
port and adjust its length so that it makes twice 
as many vibrations per minute as the first pendulum. 

3. Kepeat the experiment, determining the length 
which will make three times as many vibrations as 
the first. Eecord your results, filling out the columns 
of ratios. 

4. Do you observe any important relation between 
the length and the number of vibrations of a pendu- 
lum ? 



THE PENDULUM. 



sa 



No. 


Length. 


Eatio of 
lengths. 


Vibrations. 


Eatio of 
vibrations. 













84 EXPERIMENTAL PHYSICS. 

Experiment XXXIII. 
The Pendulum. 

The Parallelogram of Forces. 
Apparatus. — Drawing instruments and scale. 

Directions. 1. By means of the parallelogram of 
forces, resolve the weight of the pendulum into two 
forces, one of which produces the motion and the 
other the pull on the thread, (assume weight as 100 g., 
length of pendulum 2 m., and that the pendulum bob 
is 20 cm. to the right). 

2. In a like manner determine the magnitude of 
the forces when the pendulum is 40 cm. to the right. 

3. Draw another diagram, assuming the weight as 
200 g,, the pendulum being 40 cm. to the right, 
record your results and write your answers to the 
following questions : 

a. Why does not the greater force acting on the 
pendulum at 40 cm. quicken the rate of vibration ? 

b. Why does not does not doubling the weight of 
a pendulum, thereby increasing the force which pro- 
duces motion, quicken the rate of the pendulum ? 

c. What would be the effect if the force of gravity 
could be increased without changing the mass of the 
pendulum ? 



THE PENDULUM. 



85 



No. 


Weight of pendulum. 


Magnitude of force, ; 


• 


100 g. 




2 


100 g. 




3 


200 g. 




4 


200 g. 





86 



EXPERIMENTAL PHYSICS. 



Experiment XXXIV. 
Work. 

Apparatus. — A piece of hard wood 2x4x150 cm. 
wrth the upper side reduced parallel to the grain, as 
shown at A, Fig. 18. Several small holes should be 
bored through the strip of wood about 20 cm. apart, 
commencing near one end, to which a pulley is at- 
tached ; a set of weights ; retort stand ; spirit level ; 
mirror scale ; wire nail ; cotton thread. 




Fig. 18. 

Directions. 1. Tie the strip of wood to the arm 
of the retort stand, using twine or wire passed through 
one of the holes. Stretch a piece of thread from a 
tack driven in the lower part of the inclined strip to 
a wire nail driven into the table. Make this thread 
exactly horizontal, using the spirit level and great 
care, as it is used as the reference line for all measure- 
ments. 



WORK. 87 



OO EXPERIMENTAL PHYSICS. 

2. Hang a weight of several hundred grams on the 
carriage, and determine the weight which must be at- 
tached to the end of the thread which passes from 
the carriage over the pulley at the top of the inclined 
strip, to cause the carriage and load to roll steadily 
up hill when started. 

3. Determine the weight which will allow the car- 
riage and load to roll steadily down hill when started. 

4. If the motion of the carriage up hill and down 
hill was of the same nature, i. e., if, in each case, the 
increase in velocity was about the same for a given 
distance, the difference between the weights deter- 
mined in 2 and 3 will be twice the friction and the 
average of the two weights will be the force actually 
used in doing work. 

5. Make two marks on the inclined strip 50 or 60 
cm. apart, and measure, with the mirror scale, the 
vertical distance of each above the cotton thread. 

6. Compare the work done, as computed from the 
distance the carriage moved (the 50 or 60 cm. men- 
tioned in 5), and the resistance; with the product of 
the weight of carriage and load and the vertical dis- 
tance it was raised. 

7. Vary the load and repeat the experiment. 

Note. — The carriage used bad better be purcbased unless the 
teacber is possessed of considerable mecbanical skill. 



WORK. 89 



90 EXPERIMENTAL PHYSICS. 

Experiment XXXV. 

The Lever, 

Apparatus. — The wooden bar used in Exp. 24, 
with a wire about 4 era . long and 2 mm. in diameter, 
inserted in the center, and small screw-eyes 5 cm. 
apart in one edge ; a set of weights from 10 to 1000 
g. ; two retort stands ; a pulley ; twine ; a wire hook. 



tr 



Fig. 19. 

Directions. 1. Tie twine to the center wire, sup- 
port the bar as shown in Fig. 19, and balance it by cut- 
ting off the heavy end or winding wire around the 
light end. 

2. Suspend the 1 k. weight 5 cm. from the ful- 
crum. Balance it with the 200 g. weight, recording 
your results in the proper place. Remove the 200 g. 
weight. 

3. Suspend 300 g. 30 cm. from the fulcrum on the 
side opposite the 1 k. weight, and balance the lever 
by suspending another weight at some other point. 



THE LEVER. 91 



92 EXPERIMENTAL PHYSICS. 

4. Repeat 2 several times, varying the weights 
and their positions. 

5. With the aid of a pulley supported from a sec- 
ond retort stand, test the law indicated above, us- 
ing the bar as a lever of the second class, of the 
third class. 

4. Write the law of the lever, as shown by your 
experiment. 

Optional. — Test the law when the forces are not 
parallel. 

Note. — The student will observe that the problems of the 
lever are simply special cases under the composition of parallel 
forces in which the magnitude of the resultant is not required, 
and in which the relative magnitude of the components is deter- 
mined by the location of the point of application of the resultant. 



THE LEVER, 



93 



Power. 


Power arm. 


Product. 


Weight. 


Weight 
arm. 


Product. 















94 EXPERIMENTAL PHYSICS. 

Experiment XXXVI. 

The Pulley, 

Apparatus. — Two double sheave and two single 
sheave pulleys, such as may be found in any hardware 
store ; a set of weights ; cord ; the wide board. 

Directions. 1. Arrange a combination of pulleys, 
having three parts of the cord. Make a loop in the 
free end of the cord in which to hang the weights. 
Hang 1500 g. on the movable pulley, and find what 
weight will balance it. 

2. Find what weight must be attached to the mov- 
able pulley to balance 200 g. applied to the cord. 

3. Arrange a combination having 4 parts of the 
cord and repeat the experiments above. 

4. Determine the friction of the last system, by 
placing a small added weight in the power loop, 
which shall cause it to move slowly down without in- 
creasing its velocity. Now diminish the weight 
until it moves slowly up. The difference is twice 
the friction. 

4. Write the law of the pulley. 
Record in col. A the No. of movable pulleys. 
" " fixed " 

distance the power moved. 
" " weight " in the 

product of P. and distance it 
tt a -yy tt u " 



it it it 


B 


a a tt 


C 


tt tt tt 


D 


same time. 




Record in " 


E 


moved. 




Record " " 


F 


moved. 





THE PULLEY. 



95 



Exp. 



»• B - * "M" *• W. J£- 



96 EXPERIMENTAL PHYSICS. 

Experiment XXXVII. 

Wheel and Axle. 

The student may devise experiments demonstrating 
the law of the wheel and axle, recording their results 
in the table on the page opposite. 

Suggestion. — A satisfactory wheel and axle may be obtained 
by sawing wheels 20 and 5 cm. respectively in diameter, nailing 
them together, inserting a piece of T 8 ff stubbs steel in the center 
and having them turned true. The device may be supported on 
two boards 2x5x50 cm. nailed to a base about 10 cm. apart and 
have a V cut in the top of each upright. 

Experiment XXXVIII. 

Inclined Plane. 

Repeat Exp. 34, deducing the law of the inclined 
plane. 



WHEEL AND AXLE AND INCLINED PLANE. 



97 



Exp. 


W. 


P. 


Wheel. 


Axle. 


Work done. 


E. 


D. 


C. 


r. 


d. 


e. 


P. 


W. 























Exp. 



Length. 



Weight. W X 1. P X h. 



98 EXPERIMENTAL PHYSICS. 

Experiment XXXIX. 

Expansion. 

Apparatus. — A metal tube arranged as in Appen- 
dix F; a flask ; retort stand ; thermometer ; Bunsen 
burner or lamp ; battery ; electric bell, or a galva- 
nometer ; 2 pieces of rubber tubing 20 cm. long. 



Fig. 20. 

Directions. 1. Arrange the apparatus as in Fig. 
20, except the flask connection which should be made 
after the first measurement of length is completed. 

2. Turn up the micrometer screw until the electric 
bell shows contact with the screws at each end of the 
tube. Record this position of the screw, and the 
temperature indicated by the thermometer, repeat- 



EXPANSION. 9& 



100 EXPERIMENTAL PHYSICS. 

ing these observations at intervals of a minute or two 
until assured that the tube and thermometer have 
come to the temperature of the room. 

3. Turn the micrometer screw back one revolution, 
connect the flask and heat the water. When steam 
issues from the escape-tube and the thermometer in- 
dicates the boiling point for the given atmospheric 
pressure, and when the micrometer shows that the 
tube has reached a constant length, measure this 
length, recording it with the new temperature. 

4. Allow the apparatus to cool down to the tem- 
perature of the room, and repeat the first set of ex- 
periments. 

5. Measure the length of the bar at the tempera- 
ture of the room, using a mirror scale, reduce the 
length to inches. 

6. Compute the coefficient of expansion, or the 
amount of expansion per unit length of bar, per 
degree. 

Note. — The length of the bar should be reduced to 0° C. to 
insure perfect accuracy, but the length taken at ordinary temper- 
atures is sufficiently accurate for our purpose. Always see that 
the escape-tube is in contact with the nail in the support near it 
when any measurement is taken. Inches and fractions are used 
in this experiment, because the ordinary machinist cannot supply 
a metric screw. 



EXPANSION. 101 



102 EXPERIMENTAL PHYSICS. 

Experiment XL. 
Testing a Mercury Thermometer. 

Apparatus. — A thermometer ; tin cup ; pounded 
ice*; a half pound baking powder can with a hole in 
the bottom ; a liter flask ; a Bunsen burner. 

Directions. 1. Support the baking powder can 
on a small ring of a retort stand, with the tin cup 
to catch the drip; place the thermometer in the bak- 
ing powder can ; pack ice about it, having the zero 
point just visible above the surface. 

2. When you are positive that the 
mercury column has reached its lowest 
point, read the temperature indicated 
using a lens to estimate tenths of the 
smallest divisions of the scale. 

3. Arrange the thermometer in the 
flask, the bulb being above the water, as 
shown in the figure (one hole in the 
cork is sufficient if deep grooves be cut / 
in the side for the escape of the steam). [ 

4. Apply heat, and, after the water } 
which at first condensed on the upper 
part of the flask entirely disappears and ^Tfo^ZT 
the mercury column is at rest, read the temperature 
as before, and fill out the blank opposite. 

5. Read the standard barometer and correct the 
observed boiling point by allowing 1° for each 27 mm. 
above or below 760. 

* To crush ice: place the piece tc7be~broken iuthe eenter^nfli "piece of 
cheesecloth of suitable size, say .ji) cm. Bquare, gal her the four comers of 
the cloth iu one hand and pound the Lee with a mallet or hammer. 




TESTING A MERCURY THERMOMETER. 103 

THERMOMETER NO 

MAKER. 

18 

FREEZING POINT ERROR 

BOILING " ERROR 



104 EXPERIMENTAL PHYSICS. 

Experiment XLI. 
Rate of Evaporation. 

Two students will work together, each observing the 
rate of evaporation in one of the can covers. 

Apparatus. — Two Jolly balances ; methyl alcohol 
(wood spirit); the covers of a half pound and a quar- 
ter pound baking powder can ; a watch ; a meter 
stick ; a thermometer ; a pair of callipers. 

Directions. 1. Bore three holes in the rim of 
each can cover, attach wires to them and suspend 
them from the hooks of the balances . 

2. Place the balances side by side that they may be 
subjected to the same conditions, pour a small amount 
of methyl alcohol into each cover and read the weight 
every five minutes for half an hour ; reduce these 
weights to grams as directed in Exp. 3, and record in 
the proper place. 

3. Each student will compute the total weight of 
alcohol evaporated by his companion, from the diam- 
eters of the vessels, and his own observations. 



RATE OF EVAPORATION. 105 

VESSEL NO. 1.— SURFACE EXPOSED. 



Time. 


Temperature. 


Weight in grams. 


Evaporation. 











VESSEL NO. 2.— SURFACE EXPOSED. 



106 EXPERIMENTAL PHYSICS. 

Experiment XLII. 
Thermal Capacity. 

Determination of the water equivalent of the calori- 
meter to be used in subsequent experiments. 

Apparatus. — A thermometer; a calorimeter — see 
Appendix G. — ; a graduated cylinder; large flat cork; 
warm water. 

Directions. 1. Dry the calorimeter thoroughly, 
place it on the cork and let it take the temperature of 
the room. 

2. Pour into it a known weight of water, say 250 
g., at a known temperature, about 10° above that of 
the room. Stir thoroughly, but not violently, for 20 
or 30 seconds, and record the temperature. 

3. Compute the water equivalent as follows: — 
Multiply the weight of the water by the number of 
degrees loss of temperature and divide this by the 
number of degrees gained by the calorimeter. 

4. Check the above, by multiplying the weight of 
the calorimeter by its specific heat. 



THERMAL CAPACITY. 107 



108 EXPERIMENTAL PHYSICS. 

Experiment XLIII. 

Latent Heat of Water. 

Apparatus. — Calorimeter with pasteboard cover ; 
500 g. of ice ; thermometer ; a platform balance ; 
flat cork ; shot. 

Directions. 1. Weigh the calorimeter, place it 
on the flat cork, pour in 200 g. of water at about 
60° C. Through a hole in the pasteboard cover, insert 
the thermometer and cover the calorimeter. 

2. Break up the ice as in Exp. 40. Stir the 
water with the thermometer, observe the temperature, 
and immediately introduce about 100 g. of ice, which 
will be sufficiently dry if no time has been lost. 

3. Stir constantly with the thermometer, and ob- 
serve the temperature as the last particles of ice melt. 

4. Weigh the calorimeter again, to determine ex- 
actly how much ice was added, and compute the latent 
heat of melting, takiDg the water equivalent of the 
calorimeter into account. 

Suggestion. — Determine, 1st. the number of calories lost by 
the warm water, and the calorimeter. 

2d. The number gained by the melted ice as it was raised to the 
final temperature of the mixture. 

3d. The number required to melt the ice, and finally the num- 
ber required to melt 1 k. of ice. 



LATENT HEAT OF WATER. 109 



110 EXPERIMENTAL PHYSICS. 

Experiment XLIV. 

Latent Heat of Steam. 

Apparatus. — A flask ; glass tubing ; calorimeter 
with pasteboard cover; thermometer; platform bal- 
ance ; Bunsen burner and retort stand ; a watch ; 
also a valve to catch the condensed steam, made as 
follows: draw out one end of a piece of large glass 
tubing 15 cm. lung and bend the small end at right 
angles; insert a cork with a piece of tube 15 cm. long 



in the large end. 




Fig. 22. 

Directions. 1. Weigh the calorimeter ; pour 250 
g. of water at the temperature of the room into it. 

2. Connect the apparatus as shown in Fig. 22, and 
apply heat. When the steam is flowing strongly- 
through the tube, turn up the trap, to allow any con- 
densed steam to return to the flask. 



LATENT HEAT OF STEAM. Ill 



112 EXPERIMENTAL PHYSICS. 

3. Place the calorimeter on a piece of cork; record 
the temperature of the water in it, and the time, and 
condense enough steam to raise the temperature 15 
or 20 degrees. Stir the water gently with the ther- 
mometer as it heats, keeping the calorimeter covered 
as much as possible; record the time when the con- 
densation ceases and observe the loss of temperature 
by radiation during the next minute. 

4. Ascertain the weight of the steam which has 
been condensed and calculate the number of the heat 
units absorbed by the water. 

Note. — It is obvious, that the admission of water condensed 
in the trap, would involve serious error ; should the trap become 
full, or nearly so, invert it and after the water has returned to the 
flask, proceed as before. 

The temperature to which the water is raised must be corrected 
for radiation, as follows : Multiply the average loss per minute, 
by the number of minutes occupied in beating, and add this 
amount to the observed temperature. The boiling point must be 
corrected for atmospheric pressure as in Exp. 40. The water 
equivalent of the calorimeter must be added to the weight of 
water used. The heat derived from the condensed steam, as it 
coo.s from the boiling point to the final temperature of the water 
in the calorimeter, must be subtracted from the amount absorbed 
by the water, and the remainder divided by the weight of steam 
condensed. 



LATENT HEAT OF STEAM. 113 



314 EXPERIMENTAL PHYSICS. 

Experiment XLY. 
Specific Heat. 

Apparatus. — Calorimeter ; thermometer ; about 
500 g. of thin sheet lead ; thread ; the Jolly bal- 
ance ; one of the small double boilers, sold for kitchen 
use ; a watch ; a flat cork 

Directions. 1. Tie the thread around the sheet 
lead, roll into a loose coil, keeping the end of the 
thread outside. Place it in the upper part of the 
double boiler, in the lower part of which, water is boil- 
ing. Through a hole in the cover, insert the ther- 
mometer beside the coil. 

2. Pour 250 g. of water into the calorimeter and 
allow it to take the temperature of the room. 

3. When the lead has reached a stationary temper- 
ature, which will b^ slightly above the boiling point 
for the given pressure; remove the thermometer; let it 
cool a few minutes, then determine the temperature 
of the water with it. 

4. Lift the lead by the thread and lower it into the 
calorimeter, which should rest on the cork. 

5. Stir with the thermometer, observing and re- 
cording the temperature every half minute until it 
begins to fall. 

6. Determine the specific heat as follows : find 
the number of calories gained by the water, divide 
this quantity by the product of the weight of the 
lead in kilograms and its fall of temperature. 

Optional. — Correct the temperature of the water 
for radiation^as in Exp. 44. 



SPECIFIC HEAT. 115 



116 EXPERIMENTAL PHYSICS. 

Experiment XLVI. 

Yibrating Strings. 

Relation betiveen the length and the number of 
vibrations. 

Apparatus. — The wide board; three supports, 
see Exp. 8 ; 21m. of No. 18 brass spring wire ; a 
screw-eye ; stout cord 1 m. long ; retort stand, from 
which a weight is suspended by fine wire ; smoked 
paper ; photographer's varnish ; a pulley ; a wire 
pen made from No. 26 brass spring wire, 14 cm. long. 
Twist one end of the wire into a short spiral spring, 
d ; and 1 cm. from the other^end, attach a second 
piece of wire, c Z>, as in Fig. 23. Make a rectangu- 

d A 

c h c d" e 

Fig. 23. 
lar bend at c. Slip the No. 18 wire through the loop 
c b, and solder the end of the spring d to it. 

Directions. 1. Place the wide board on the table, 

drive a round headed 

screw in one edge, and 

attach the pulley in a 

Fig, 24. similar position on the 

oth er. 

2. Stretch the No. 18 wire from the screw, over the 
pulley, and to the spring balance. Fasten a screw- 
eye in the floor, tie the ring of the balance to it with 
the cord in such manner that the tension of the wire 
can be controlled. 



VIBRATING STRINGS. 117 



118 



EXPERIMENTAL PHYSICS. 



3. Connect the pendulum with the marker so that a 
very slight displacement to the 
left will raise the marker from the 
paper. Thus the marker will be 
off the paper half the time. 

Make the tension 16 lbs.; set 
two of the bridges 2 m. apart; 
place a strip of smoked paper be- 




neath the marker; set the pendulum in mo- 
tion, taking care that it does not cause the 
bottom of the loop c, Fig. 23, to strike the 
wire. Set the string in vibration in a hori- 
zontal plane, and draw the smoked paper I 
slowly along. The marker will trace a sinu- fe 
ous curve, and the vibrations of the wire may be 
readily counted. 

5. Place the third bridge between the others and 
determine the vibrations when the string is 1 m. 
long.* 

6. Obtain a trace with the bridge in other positions, 
as at 150 and 175 mm. Coat the smoked paper with 

* If the third bridge changes the height of the wire, it may change the 
time during which the trace is made, hence it is well to hold the vibrating 
string down on the bridge with the fingers, or to fasten the bridge in place 
on the wide board with wood screws, and to hold the vibrating string down 
on the rest, by driving a double-pointed tack over it. 



VIBRATING STRINGS. 



119 



Size of wire. 


Length. 


Tension. 


Vibration. 








* 



120 EXPERIMENTAL PHYSICS. 

varnish and when dry, paste the records on the opposite 
page. 

7. What relation exists between rate of vibration 
and length? 

Experiment XL VII. 
Vibrating Strings. 

Apparatus. — That used in Exp. 46. 

Directions. 1. Obtain a duplicate trace with the 
No. 18 wire, the length being 2 m., and the tension, 
16 lbs. 

2. With the same length of wire, determine the 
vibrations, when the tension is 25 lbs. 

3. Repeat, with tension 4 lbs. 

5. What law connects the tension with the number 
of vibrations ? 

Note. — This apparatus may be used to prove the remaining 
law of vibrating strings, and also to produce a compound curve 
showing the presence of overtones. 



VIBRATING STRINGS. 121 



122 EXPERIMENTAL PHYSICS. 

Experiment XL VIII. 
Vibrating Strings. 

Relation between pitch and rate of vibration. 

Apparatus. — Two tuning forks giving notes an 
octave apart."" The apparatus used in Exp. 47, with 
the No. 24 wire under a tension of 25 lbs. 

Directions. 1. Tune the strings to the lowest fork, 
by changing the length, recording the length. 

2. Without changing the tension, tune the string 
to the second fork, recording the length. 

3. Make the tension 16 lbs., and repeat. 

4. What is the relation between pitch and length? 
— between pitch and rate of vibration? 

* The ordinary A and C forks to be found at the music store may be used. 



VIBRATING STRINGS. 



123 



Note. 


Tension. 


Length. 


Ratio of 
vibration. 











124 EXPERIMENTAL PHYSICS. 

Experiment XLIX. 
Pitch of a Tuning-Fork. 

Two students ivill work together. 
Apparatus. — A watch; a tuning-fork, not above 
300 vibrations per second; some strips of smoked 
paper; photographer's varnish; a board 25 by 60 cm. 
the tuning fork support *; the lime marker f; the 
pendulum support; the small spring used on the Jolly 
balance; a set of weights; cotton thread. 




Fig. 26. 



♦The tuning-fork support consists of a piece of 2 inch plank 10 cm. wide 
and 20 cm. long, cut down to one inch thick at one end. and having a hole 
in the thick end into which the stem of the fork is driven. A screw rounded 
onthe end is provided to adjust the bristle attached to the fork to the 
smoked paper. The lower part of the support beneath the fork is cut out to 
a depth of say 5 mm. to allow the smoked paper to pass through, and the 
support is attached to the base by short strips of sheet brass. 

t The time marker is a piece of brass wire about 12 cm. long bent twice 
at right angles, the long end being inserted in a hole in a block, which is 
fastened to the base by a thumb-screw; a chair-round standing in a hole in 
the base carries a piece of wood about 8 cm. square and 15 cm. long, which 
may be clamped in any desired position. From a double pointed tack in the 
lower side the small spring is suspended. 



PITCH OF A TUNING FORK. 125 



126 EXPERIMENTAL PHYSICS. 

Directions. 1. Attach a bristle about 15 mm. 
long to one prong of the fork and adjust it to the 
smoked paper. 

2. Adjust the time marker so that the point which 
rests on the smoked paper is about 1 mm. in front of, 
and a little to one side of the end of the bristle. Tie 
one end of a piece of thread to the marker, and the 
other end to the spring, so that the marker will be 
lifted from the paper a short time during every vibra- 
tion of the spring. 

3. Suspend about 30 g. from the spring, pull down 
the weight and release it, thus causing longitudinal 
vibrations in the spring; watch in hand count the 
vibrations made in 20 or 30 seconds, and record the 
time of the pendulum. 

4. Set the fork and the spring in vibration and 
draw the smoked paper quickly through beneath 
bristle and marker;* — the former will make a sinuous 
trace, and the latter an interrupted line beside it. 

5. Count the number of vibrations of the fork be- 
tween the end of one of the time marks, and the end 
of another — not the beginning — since the time re- 
quired for the marker to fall back to the paper de- 
pends upon the distance it has to fall, and hence 
upon the amplitude of vibration of the spring. 

6. Coat the paper with varnish and fasten it on 
the opposite page. 

* The smoked paper may be attached to a piece of glass, and the appa 
ratus inclined so that the glass will slide slowly d< iwn < >f its < >wn accord when 
released by starting the spring. 



PITCH OF A TUNING FORK. 127 



128 



EXPERIMENTAL PHYSICS. 



Experiment L. 

Telocity of Sound.* 

Apparatus. — A snare drum or a fish-horn; a single- 
stroke electric bell; 1,000 feet of two conductor office 
wire cable on reel; a thermometer; a battery; a 
mercury contact (see Appendix I); also a frame and 
pendulum, (Fig. 27) 10 cm. wide, and 110 cm. tall. 
Near the top, screw in an 8-inch curtain hook; from 
this suspend by two No. 30 wires a heavy weight 
(say 1 k) to the bottom of which is soldered a short 
piece of wire filed to a point. 




Fig. 27. 



* It is suggested that the whole class go to some quiet and nearly level 
locality to perform this experiment. 



VELOCITY OF SOUND. 129 



130 EXPERIMENTAL PHYSICS. 

Directions. 1. Fasten the electric bell on the 
side of the reel, connect one wire to each binding post 
of the bell; beginning at the free end, sew small 
pieces of leather properly numbered to the cable at 
points 100 feet apart. 

2. Fasten the pendulum frame to a post or a tree; 
arrange the pendulum, battery and mercury, contact 
in circuit, and connect with the cable wires; adjust 
the mercury contact so that the circuit is closed 
when the pendulum is at rest. 

3. Station one pupil in front of the pendulum; — 
set it in motion, and have the pupil beat the drum as 
the pendulum closes the circuit. The sound of the 
drum will coincide with that of the bell. If the rest 
now retire, unwinding the cable, the sound of the 
drum will be heard after the stroke of the bell, the 
interval increasing as the distance increases. It is 
obvious that when the sound of the drum again co- 
incides with that of the bell it occupies the time of 
one vibration of the pendulum in traveling from the 
drummer to the bell. Determine this distance, re- 
cording it in the proper place, with the temperature. 

4. Determine the period of the pendulum by count- 
ing its vibrations for a minute or more, and compute 
the velocity of sound. 

5. Repeat the experiment, retiring in other direc- 
tions. 



VELOCITY OF SOUND. 131 



132 EXPERIMENTAL PHYSICS. 

Experiment LI. 
Velocity of Sound. 

Wave length. 

Apparatus. — The diapason whose rate of vibra- 
tion has just been determined; cylinder used in Exp. 
6; mirror scale; thermometer. 

Directions. 1. Hold the vibrating diapason over, 
and as close as possible to the mouth of the cylinder; 
pour in water slowly, noting the length of the column 
which yields the loudest note; record this length and 
the temperature. 

2. Repeat three times, taking the average length 
of the air column, increased by one-fourth of the 
diameter of the cylinder used as one-fourth of the wave 
length of the fork. This multiplied by the rate of 
vibration of the fork will give the velocity of sound at 
the given temperature. 

3. Determine the effect of a change in temperature 
upon the velocity by taking the apparatus to a cold 
room, if in winter, or by packing the cylinder in ice, if 
in summer, and making a similar determination. 

Optional. — Fill the cylinder with carbon dioxide, 
and repeat the determination. 



VELOCITY OF SOUND. 133 



134 EXPERIMENTAL PHYSICS. 

Experiment LII. 
Interference of Sound. 

Whiting's method. — Two students xoill work together. 

Apparatus. — The diapason used in the last ex- 
periment; a piece of £ inch rubber hose about 80 cm. 
long; a tin Y made to fit the hose. 

Directions. 1. Make an ink mark in the middle 
of the hose; slip the ends on the Y tube. 

2. As one student holds the open end of the Y 
tube to his ear let the other touch the hose in the 
middle with the handle of the vibrating fork, moving 
it by short steps toward his right until a position of 
approximate silence is found. Measure and record the 
distance of this point from the centre, and explore the 
left side of the tube for a similar point. 

3. The students will now change places and repeat 
the experiment. 

4. Compare the distance just determined with the 
wave length of the fork determined in Exp. 50, and 
write full explanation of the change in loudness of 
the sound as the position of the fork on the hose is 
changed. 



INTERFERENCE OF SOUND. 135 



136 



EXPERIMENTAL PHYSICS. 



Experiment LIII. 
Photometry. 

Bumford's Method. 

Apparatus. — A mirror scale; a piece of white card- 
board 2 cm. square; two thumb-tacks; a meter stick; 
a chair-round with a block of wood as a support; five 
small candles; a block of wood 2x5x5 cm, to carry- 
one of the candles, and one 2x5x12 cm. for the other 
four. 

PART I. 

Directions. 1. Arrange the apparatus as shown 
in Fig. 28, placing the chair-round 5 cm., and the 
single candle 30 cm. from the screen. 

2. Place the board carrying the four candles about 
30 cm. from the screen, the line joining the candles 
being at right angles to the line from the chair-round 
to them. 





Fig. 

3. Move the four candles toward, or away from the 
screen until the middle of the shadow which they 



PHOTOMETKY. 137 



138 EXPERIMENTAL PHYSICS. 

cast appears just as dark as that cast by the single 
candle. 

4. Measure the distances from the shadows to the 
lights casting them. 

PART II. 
Directions. 1. Substitute the lamp for the four 
candles, placing the edge of the flame towards its 
shadow; — move it towards, or away from the pencil, 
making the shadows of equal density. 

2. Measure the distances from the screen to the 
lights and compute the candle power of the lamp. 

3. Make a determination of the candle power with 
the side of the flame toward the shadow. 



PHOTOMETRY. 139 



140 EXPERIMENTAL PHYSICS 

Experiment LIV. 

Law of Reflection of Light. 

Apparatus. — A plane mirror 10x20 cm., (common 
looking glass); a block of wood (Exp. 26); two large 
rubber bands; a protractor; the wide board; a large 
sheet of paper; thumb-tacks; pins. 

Directions. 1, Fasten the paper on the wide 
board; draw a line in the middle, attach the mirror 
to the block with the rubber band, and place it on 
the paper with the reflecting surface and the line just 
drawn in the same vertical plane. 

2. Set a pin about 20 cm. in the front of the mirror, 
toward one end. Set a second pin at some point from 
which the reflection of the first pin may be seen. Set 
a third pin between the second and the reflection of 
the first. 

3. Erect a perpendicular to the face of the mirror 
at the point of intersection, and measure the angle 
of incidence and the angle of reflection with a pro- 
tractor. 

4. Repeat the experiment several times, varying 
the positions of the object and the eye as much as 
possible, recording your results in the proper place and 
indicating the various positions of the object by a 
sketch . 



LAW OF REFLECTION OF LIGHT. 



141 



Position. 


Angles. 
Incidence. 


Reflection. 


Error. 











142 EXPERIMENTAL PHYSICS. 

Experiment LV. 
Plane Mirrors. 

Apparatus. — The same as in Exp. 54, a clean sheet 
of paper being substituted for the one used. 

Directions. 1 . Draw a center line on the paper 
and place the mirror in position; set a black pin 40 
cm. in front of the mirror near one side, as at 1, Fig. 
29; assume a point of sight, as 2, and determine the 
line in which the image appears by setting 3 in line 
between 2 and the image of 1*. 



Fig. 29. 

2. Repeat the operation from other points of sight 
as 4 and 6, determining the direction of the image 
from each. 

3. Draw pencil lines connecting 2 and 3 — 4 and 5, 
etc., and prolong them to their intersection. 

4. Draw a line from 1, perpendicular to the plane 
of the mirror. Measure the distance from 1 to the 
reflecting surface of the mirror, and to the image. 

5. Set 1 nearer the mirror and repeat. 

6. What relation between the position of an ob- 
ject and its image? 

* See that the third pin and not it* image is in this line. 



PLANE MIRRORS. 



143 



Distances. 


Error. 


Object. 


Image. 










144 EXPERIMENTAL PHYSICS. 

Experiment LVI. 
Convex Lens. 

Determining Focal Length. 

Apparatus. — A converging lens;* a meter stick; 
three blocks 1 by 3 by 7 cm. are cut out to fit the 
meter stick, and a piece of sheet brass 1 cm. wide is 
fixed over the opening with 
two screws. Tack to the 
side of one of them a 
piece of thin card-board 
about 15x20 cm. to serve 
as a screen. In the cen- 
tre of a second block attach Fig. 30. 
a piece of No. 18 or 20 wire 5 cm. long. Make 
a saw-cut about 2 mm. wide and 5 mm. deep across 
the remaining block, in which to support a lens. Cut 
a hole near one side of this block, so that the scale on 
the meter stick may be seen through it. Fig. 30. 

Directions. 1. If the sun is shining, place the 
screen and lens in position on the meter sticks, and, 
looking at the screen from the side away from the 
lens, move the lens back and forth until a sharp 
image of the sun appears upon it. 

2. Measure the distance from the lens to the screen. 
Repeat the experiment several times, taking the mean 

* Spectacle leases will answer, Nos. 6 to 10 proving most satisfactory, 
but round lenses in a rubber frame are more convenient and the cost is 
trifling— see Fig. 30. The number of a spectacle lens is its focal length in 
inches. 



CONVEX LENS. 145 



146 EXPERIMENTAL PHYSICS. 

of the measurements as the principal focal length of 
the lens. 

Alternate 1. If the sky is cloudy, remove the screen, 
substituting the block and wire: place the wire about 
30 cm. from the end of the stick with the lens beyond it. 
Point the stick at a distant spire or some other well 
denned object, and move the lens back and forth 
along the rod until the wire and the image of the object 
coincide. If the head is moved from side to side, the 
one furthest from the eye will appear to move with 
respect to the other, in the same direction as the head. 
When there is no change in the relative position as the 
head moves, the distance from the lens to the pin is 
the focal length. Why? 



CONVEX LENS. 14T 



148 EXPERIMENTAL PHYSICS. 

Experiment LVII. 
Law of the Convex Lens. 

Conjugate Foci. 

Apparatus. — The optical bench used in Exp. 55; 
a candle; a piece of tin-type plate about 9 by 12 cm. 
tacked to a block like the lens carrier, Fig. 30; a hole 
about 5 mm. in diameter should be drilled in the tin- 
type plate at the height of the centre of the lens. 




Fig. 31. 

Directions. 1. Arrange the apparatus as in Fig. 
31, the tin-type plate and the screen being exactly 1 
m. apart. Move the lens until a distinct image of the 
hole in the plate (not the candle flame) appears on 
the screen. Record the distances from the lens to 
the object, and to the image. 

2. See whether any other position of the lens will 
give a distinct image, and if one be found record the 
position as before. 



LAW OF THE CONVEX LENS. 149 



150 EXPERIMENTAL PHYSICS. 

3. Repeat the above determination with the plate 
and screen, 80, 60 and 40 cm. apart. 

4. Compute the focal length of the lens by the 
formula 

1 _L . I 

F — D ' Di 
in which F is the principal focal length of the lens 
and D and Di the distances from the lens to the ob- 
ject and to the image respectively. Compare this 
quantity with the focal length found in Exp. 56. 



[law of the convex lens. 



151 



Do 


Di 


1 
Do 


1 
D i 


Computed 
Focal length. 


Errors. 















152 EXPERIMENTAL PHYSICS. 

Experiment LVIII. 

Lilies of Magnetic Force. 

Apparatus. — Two magnets, 10 cm. long, made of 
clock-spring or wide crinoline steel; a piece of glass 
10x20 cm.; a piece of bunting containing fine iron 
filings; a solution of tannin; sheets of unsized paper 
10x20 cm. ; a magnetic needle, made by magnetizing 
half a sewing needle, and suspending it with a piece 
of thread. 

Directions. 1. Place the glass over the magnet, 
and sift the iron filings evenly over it, tapping the 
glass gently meanwhile. 

2. When the curves are clear and distinct, suspend 
the needle over any one of them and note the position 
of the needle with respect to the curve. Move the 
needle along the curve, noting its action. What 
does the curve indicate concerning the direction of 
the resultant of the forces acting on the magnetic 
needle ? 

3. Carefully lift the glass from the magnet, moisten 
a sheet of paper with the tannin solution, and place 
it on the glass. Place a piece of blotting-paper over 
this, and press the moist paper gently down upon the 
glass. Now place the glass and paper in a warm 
place. When dry the iron filings may be brushed 
off, leaving an ink spot on the paper wherever iron 
comes in contact with the tannin solution. 

Fasten this paper in the book, opposite this page. 



LINES OF MAGNETIC FORCE. 153 



154 EXPERIMENTAL PHYSICS. 

4. In the same manner obtain the following addi- 
tional curves: 

a. Two bar magnets with like poles near each other. 

b. Two bar magnets with unlike poles near each 
other. 

c. A bar magnet with a j3iece of soft iron near it. 

Experiment LIX. 

Distribution of Magnetism. 

Apparatus. — A Jolly balance; thread; a small 
nail ; a magnet about 20 cm. long, made of clock- 
spring, or a bar of tool-steel tempered very hard; a 
red or a blue lead-pencil. 

Directions. 1. Mark points 1 cm. apart on the 
magnet with the colored pencil. 

2. Using spring best adapted to the strength of the 
magnet, suspend a small nail from the hook of the 
balance, by means of a thread. 

3. Read and record the position of the index, and 
placing the nail in contact with the end of the mag- 
net, move the magnet slowly downward, keeping it 
horizontal, and watching the index. Record the 
force required to pull the nail from the magnet. 

4. Determine in like manner the force required to 
pull the nail from the magnet at each of the points 
marked, repeating the test several times, at each of 
the points near the end of the magnet, and taking the 
average as the force to be recorded. 



DISTKIBUTION OF MAGNETISM. 



155 



Balance Headings. 



With Magnet. 



156 EXPERIMENTAL PHYSICS. 

Obtain a piece of paper ruled in small squares and 
plat a curve representing the force of the magnet at 
each point as follows: 

Draw a horizontal line as many squares long as the 
magnet is cm. long. On each vertical line lay off a 
distance from the horizontal line which will represent 
the strength of the magnet at this point. If the dis- 
tance is measured upward for the north-seeking end, 
measure downward for the south-seeking end. 

Experiment LX. 
The Galvanometer. 

Relation between the chemical energy of a current, 

and the deflection caused by it. 

Apparatus.* — A tangent galvanometer and scale; 

a rheocord and bridge; a commutator; a voltameter; 

two cells freshly charged; a watch; the wide board 

and long spring for weighing. (See Appendix K.) 

Directions. 1. Set up the galvanometer, as di- 
rected in Appendix J; clean, dry and accurately 
weigh the anode and cathode, using the long spring. 

2. Connect the apparatus, except the (Q)3 

voltameter which must not be inserted 
as yet, as shown in the sketch, in f — 7r - 
which B represents the battery, V the L_^^_ZP 
voltameter, R the rheocord, C the Fig. 32. 

* The construction of the electrical apparatus required for this and sub- 
sequent experiments, is described in Appendix J. 




THE GALVANOMETER, 157 



158 EXPERIMENTAL PHYSICS. 

commutator, and G the galvanometer. Lead the 
current through the 10 convolutions and insert rheo- 
cord resistance enough to bring the deflection on the 
scale. 

3. Now insert the voltameter, noting the exact 
time when the current begins to flow through it, 
read the deflection; reverse the current at the com- 
mutator and read again. Keep this deflection con- 
stant during half an hour, by varying the rheocord 
resistance. 

4. At the close of the half hour break the current, 
remove, wash thoroughly, and dry the cathode, de- 
termine its increase in weight. 

5. Repeat the experiment, increasing the resistance 
so as to bring the deflection down to about 20°. 

6. Determine the relation between the deflection 
and the weight of copper deposited. 



THE GALVANOMETER. 



159 



Time. 


Weight of Cathode. 


Copper 
deposited. 


Deflection. 


Before. 


After. 













160 EXPERIMENTAL PHYSICS. 

Experiment LXI. 
Polarization. 

Apparatus. — A simple voltaic cell consisting o 
thin strips of zinc and copper, to which pieces of cop 
per wire are soldered, immersed in a tumbler contain 
ing dilute sulphuric acid, and bent over at the top s< 
as to clasp the side of the tumbler; the tangent gal 
vanometer. 

Directions. 1. Weigh each plate, using the lonj 
spring. 

2. Connect the cell with the 10 turn coil of th< 
galvanometer, and record the position of the needle 
Observe and carefully describe what occurs at tin 
surface of each strip of metal. 

3. Amalgamate the zinc strip,— replace it, noting 
any change in its action in the cell, and the deflection 

4. Connect the battery with the galvanometer ob- 
serving the deflection every 2 minutes for a quarter 
of an hour. 

5. At the close of this time brush away any bub- 
bles which may adhere to the copper plate and note 
the effect upon the deflection. 

6. Remove the plates, wash, dry and weigh them 
again. 

7. What is the effect of polarization ? What 
causes it ? Which plate is dissolved ? What is the 
effect of amalgamating the zinc ? the copper? 



POLARIZATION. 161 



162 EXPERIMENTAL PHYSICS. 

Experiment LXII. 

Battery Resistance. 

Apparatus. — A tangent galvanometer; commuta- 
tor; a bichromate battery. Fig. 33. 




Fig. 33. 

PART I. 

Effect of a change of distance between plates. 

Directions. 1. Using the materials of the battery 

shown in Fig. 33, set up a battery consisting of a 

single carbon and a zinc plate clamped as far apart 

as the tumbler used will permit. 

2. Connect the battery, rheocord, commutator and 
the single turn coil of the galvanometer, in circuit; 
read the deflection, reverse at the commutator and 
read again. 

3. Clamp the plates on either side of one of the 
strips used in the battery and read (he deflection. 

4. Now insert 2 m. of G-. S. wire in addition to that 
already in circuit, and repeat the measurements, 
directed in Directions 2 and 3. 



BATTERY RESISTANCE. 163 



164 EXPERIMENTAL PHYSICS. 

PART II. 

Effect of a change in the size of the plates. 
Directions. 1. Loosen the clamp and pull the 
plates up between the strips so that only one-fourth 
as much of the plates as before shall be immersed in 
the liquid. 

2. Connecting the battery as in Part I, read the 
deflection with and without the 2 m. of Gr. S. wire 
in circuit. 

3. Compare these deflections with those produced 
under similar conditions except in regard to size of 
plate. Inference. 

4. Under what conditions is the circuit most sensi- 
tive to changes in the size and distance between 
the plates? 



BATTERY RESISTANCE. 



165 



Distances 
between 
plates. 


Area 
immersed. 


External 
Resistance. 


Deflection. 


I II 













166 EXPERIMENTAL PHYSICS. 

Experiment LXIII. 

Method of Combining Cells. 

Apparatus. — Two cells of battery ; the rheocord ; 
the tangent galvanometer; and the commutator. 

Directions. 1. Connect the two cells in multiple 
arc and place them in circuit with the rheocord, com- 
mutator and the zero coil of the galvanometer, intro- 
duce resistance enough to bring the deflection on the 
scale, read and record. 

2. Insert all the rheocord resistance and read again. 

3. Connect the two cells in series with the com- 
mutator, the zero coil of the galvanometer, and 
the rheocord. Introduce the same rheocord resist- 
ance first used and read the deflection produced, 

4. Insert all the rheocord resistance and read again. 

5. Repeat the above measurements using a single 
cell. 

6. Which way of combining the cells produces the 
largest current when the external resistance is low ? 
high ? In what kind of a circuit does a single cell 
produce nearly as much current as two cells con- 
nected in series ? as two cells connected in multiple 
arc ? 



METHODS OF COMBINING CELLS. 



167 



No. of 
cells. 


How 

connected. 


External 

Resistance. 


Galvanometer readings 


Deflection. 


I 


II 















168 EXPERIMENTAL PHYSICS. 

Experiment LX1V. 
The Galvanometer. 

Determination of the reduction factor . 
Apparatus. — That used in Exp. 60. 

Directions. 1. Repeat the first part of Exp. 60, 
allowing the current to flow through the voltameter 
for an hour, keeping the deflection constant; deter- 
mine the amount of copper deposited, and compute 
the magnitude of the current by applying the rule; 
an ampere of current deposits .000326 g. of copper 
per second. 

2. Now since the deflection is proportional to the 
amount of copper deposited, or energy of the current 
as shown in Exp. 60, it follows, that if we find the 
factor by which we may multiply the number repre- 
senting the deflection, to reduce it to amperes, the 
same factor will reduce any other deflection to am- 
peres. 

3. This reduction factor may be found as follows: 
Divide the weight of copper deposited by the num- 
ber of seconds, multiplied by .0003:26. This will 
give the strength of the current in amperes, and if 
this be divided by the deflection, the result will be 
the current per unit length of scale or the reduction 
factor sought. 

Note. — It must be remembered that this factor applies only 
to the coil of the galvanometer used in the experiment and only 
when the scale is exactly the same distance from the mirror that 
it was when the factor was determined. 



THE GALVANOMETER. 169 



170 EXPERIMENTAL PHYSICS. 

4. Record on the opposite page the distance between 
the scale and the mirror, the number of the galvano- 
meter, its position in the laboratory, and preserve there 
all numerical work connected with this experiment. 

Experiment LXV. 
Ohms Law. 

Relation between electro-motive, force and current. 
Apparatus. — A tangent galvanometer; three small 
Daniel or freshly charged Grenet cells; a rheocord; a 
commutator. 

Directions. — 1. Connect the three cells in series 
with the rheocord, commutator, and the single turn 
of the galvanometer, adjust the rheocord resistance so 
that the deflection is as large as can be conveniently 
read. 

2. Reverse the current with the commutator, re- 
cording the deflection . 

3. Connect one of the cells in opposition to the 
other two, and without changing the resistance of the 
circuit in any way, read the new deflection, reverse, 
and read again. 

4. Assume E. M. F. of each cell to be a volts, and 
bearing in mind the fact that the only change in the 
circuit has been a change of E. M. F., compare the 
deflections, with E. M. F. of the battery producing 
them. Inference. 



OHMS LAW. 171 



172 



EXPERIMENTAL PHYSICS. 



Experiment LXVI. 
Ohms Law. 

Fall of Potential. 

Apparatus. — A rheocord; a battery; connecting 
wires; a tangent galvanometer; a high resistance 
made by rubbing a pencil line 1 cm. wide by 20 cm. 
long on a piece of ground glass 10 by 20 cm. For 
contacts, clamp pieces of tinfoil, folded several times, 
and placed beneath small plates of copper, over the 
ends of the pencil mark, by means of strips of wood \ 
by 2 by 13 cm. drawn together by wood screws. 
Fig. 34. 

The resistance will vary greatly in different cases, 
depending upon the grains 
of the glass and the lead 
pencil used, and should be 
adjusted to meet the re- 
quirements of the experi- 
ments in hand by changing 

either the width of the line, or the distance between 
the clamps. 




Fig. 34. 



Directions. 1. Connect the battery B. with the 
rheocord, the current passing through the two meters 
of bare wire from to Q. Fig. 35. 

2. Connect the 80 turn coil of the galvanometer 
and pencil mark resistance as shown, one wire going 



OHMS LAW. 173 




174 EXPERIMENTAL PHYSICS. 

to the binding post 0, and the other to the sliding 
contact. 

3. Close the galvanometer circuit with the slider 
25 cm. from the end 
of the wire OP Q, ad- 
just the resistance so 
that the deflection shall 
be less than 10 cm. 

This done the resistance must not be altered during 
the remaining experiments. Read and record the 
deflection. 

4. Repeat the above, tapping the battery circuits at 
points 25 cm. apart, until the fall of potential for the 
whole length of the wire OPQ has been measured. 

5. Reverse the current through the wire OPQ and 
repeat the measurements in the reverse order, begin- 
ning from the end Q. 

Argument. — The fall of potential between any two points of a 
given circuit is shown above to be proportional to the lenglh 
of the wire, i. e., to the resistance between them, and thus the 
same current is maintained in each part of the cir- r 5 ohms j * 
cuit. B C D E, Fig. 36, represents an imaginary cir- 
cuit; the figures indicating the resistance of the dif- 
erent parts. If in this circuit there be a change in d l 



' < 



the total resistance without a corresponding change Fig. 36. 
in the total E. M. F., the fall of potential between any two points, 
as D and E, will be changed in an inverse ratio. 

But Exp. 63 has proven that current is proportional to differ- 
ence of potential. Hence if the total resistance of the circuit be 
changed without a corresponding change in the total E. M. F., 
the current between D and E will be changed in an inverse ratio. 

That is to say, the E. M. F. remaining the same, the current is 
inversely proportional to the total resistance of the circuit. 



OHMS LAW. 



175 



Length of 
wire (1). 


Deflection. 


Average (2). 


(2) 
(1) 


1st set. 


2d set. 


25 cm. 

50 

75 
100 
125 
150 
175 
200 











176 EXPERIMENTAL PHYSICS. 

Experiment LXYII. 
Resistance of Wires by Wheatstone's Bridge. 

Relation between length arid resistance. 

Note— The teacher should explain the Wheatstone bridge, ap- 
plying the principle proved by the last experiment. 

Apparatus. — The rheocord and bridge ; a galvan- 
oscope ; a battery ; three ordinary spools carrying 
respectively 2, 4, and 8 m. of No. 30, B . and S. gauge, 
cotton-covered copper wire. Appendix J. 

Directions. 1. The rheocord becomes an efficient 
Wheatstone's bridge when constructed as follows 




Fig. 37. 

Connect the resistance to be measured with binding 
posts A and B, Fig. 37; insert the galvanoscope be- 
tween binding posts A and E; connect the battery 
with binding posts C and D. 

The " link " is used to connect mercury cups 1 and 
2 or 1 and 3, as the resistance to be measured is large 
or small. The arms of a bridge thus formed are 1st 
from D through the coils to A, thence through the 
unknown resistance to C. 2nd, from D the bridge 
wire to the slider E, and thence through the remainder 
of the bridge wire to C. 

2. Connect mercury cups 1 and 3 with the link, 
insert 2 Mo coils between A and B, and adjust the 



WHEATSTONE BRIDGE. 



177 



Length of 
wire. 


Size of 
wire. 


Bridge reading. 


Resistance. 


1st (D). 


2d (C). 













178 EXPERIMENTAL PHYSICS. 

slider to that point of the bridge wire that sends no 
current through the galvanometer. 

3. In like manner measure the resistance of the 4 
and the 8 m. of wire, recording your results in the 
proper place and computing your results in ohms ; if 
the resistance of the 2 m. bridge spool is unknown, 
assume it to be 10 ohms. 

4. Write the relation between the resistance and 
the length of wire. 

Experiment LXVIII. 
Resistance of Wires. 

Relation between diameter and resistance. 

Apparatus. — That used in Exp. 65 with the addi- 
tion of three spools carrying 8 m. of No. 18, 24, and 
36, B. and S. gauge wire respectively. 

Directions. 1. Proceeding as in Exp. 65, meas- 
ure the resistance of each of the 8 m. spools includ- 
ing the No. 30. 

2. Compare the resistance and state and observe 
relationship between the m. and the diameter of the 
wires. 

Note. — Inspection shows that according to the B. and S. wire 
gauge the diameter of wire doubles every 6 numbers, and quite 
accurate results may be obtained if their wire as found at the 
stores is used. 

It is better however to measure the diameter with a Micrometer 
calliper. The apparatus used in Exp. 39 may be used for this 
purpose with great accuracy, if care is taken to square the end 
of the tube against which the Micrometer screw strikes. 

The diameter may also be determined as in Exp. 4. 



RESISTANCE OF WIRES. 



179 



Length of 
wire. 


Size of 
wire. 


Bridge reading. 


Resistance. 


1st (D). 


2d(D). 













180 EXPERIMENTAL PHYSICS. 

Experiment LXIX. 
Specific Resistance. 

Apparatus. — That used in Exp, 65, and a spool 
carrying two M. of No. 30 B. and S. gauge iron wire. 
It is desirable to knoiv that the three No. 30 wires 
used below are the same diameter. 

Directions. 1. Compare the resistance of the No. 
30 copper wire with the 2 m. coil of 30 G. S. wire on 
the rheocord. 

2. Substitute the iron wire and repeat the meas- 
urements. 

3. Assuming the specific resistance of copper as 
1.06 compute the relative resistances of German silver 
and iron. 



SPECIFIC KESISTANCE. 



181 



Kind of 
wire. 


Length. 


Size. 


Galvanometer readings 


Eelative 
Resistance. 


1st. 


2d. 
















W 



182 EXPERIMENTAL PHYSICS. 

Experiment LXX. 
Electromotive Forces of Batteries. 

Apparatus. — A single cell of bichromate battery 
to be measured; a Daniel or a Clark standard cell; 
the high resistance Fig. 34; a galvanoscope; a rheo- 
cord. 

Directions. 1 . Connect the apparatus as shown 
in Fig. 38 in which 
B is the battery to 
be measured, Gr the 
galvonometer, and R 
the high resistance. 
S the standard bat- Fig. 38. 

tery is connected so that its current flows through the 
wire P Q in a direction opposite to that of the bat- 
tery B. 

2. Change the high resistance as may be necessary 
to make the galvanometer sensitive to a slight change 
of position of the wire D, on wire P. 

3. Find a point on the wire OPQ that may be 
touched with wire D without sending a current 
through the galvanometer. 

4. The fall of potential along the wire P be- 
tween and D is now equal to E M F of the stan- 
dard and the distance D : 2m (the distance P 
Q) : : the E. M. F. of S : the E, M. F. of B. 

V E. M. of B. = *EL E. M. F. of S. 
OD 
Note. — If a Daniel cell is used as a standard the high resistance 
R had better be omitted. 



ELECTROMOTIVE FORCES OF BATTERIES. 183 



184 



EXPERIMENTAL PHYSICS. 



APPENDIX A. 

The Mirror Scale. 

Construct a frame like Fig. 39, the upright being about GO cm. 
high. Flow a strip of looking-glass 
5 x 50 cm. with rather thin asphal- 
tum. When it is dry fasten the 
glass and a meter stick side by side 
on a board; block up the glass so 
that it is the same height as the 
meter stick, and using a small tiy- 
square and a pointed instrument re- 
produce the scale in the centre of the 
glass; be sure that the marks cut 
through the asphaltum. The scale 
may be etched on the glass very 
quickly and conveniently by pouring . 
a few drops of hydrofluoric acid on 
it, spreading the acid over the glass : 
with a splinter of wood and allowing Fig. 39. 

it to remain there about two minutes. Wash off this acid, clean 
the glass with benzine, and fasten it to the upright. A paper 
millimeter scale will be almost as convenient as the etched scale if 
trimmed down to 1 cm. wide and pasted in the centre of the 
glass with gum tragacanth. 




APPENDIX B. 

A Modified Jolly's Balance. 

Make a frame about 50 cm. high like the sketch, by means of 
tacks, fasten a piece of looking-glass 5 cm. wide and 35 cm. long 
to the upright, paste a strip, about 1 cm. wide, cut from the end of 
a sheet of profile paper (Plate B), in the middle of the glass. 
Number every fifth mark of the profile paper with ink, beginning 
at the top. This will make a very accurate scale and although 
the readings represent neither ounces nor grams, they represent a 
definite weight and in the few cases in which it is necessary may 



CONSTRUCTION OF APPARATUS. 



185 




be reduced to grams by multiplying by the modulus of the spring 
used as directed in Exp. 3. 

Obtain from the tinsmith a tube about 12 mm. in diameter and 
20 cm. long, bore a small hole 5 cm. 
from one end; bend 5 mm. of one 
end of a piece of No. 21 spring 
brass wire 1£ m. long, through some- 
thing more than a right angle, and 
engage the hook thus formed in the 
hole in the tube; fasten the other 
end of the wire in a vise or to a 
door knob, and holding one end of 
the tube in each hand, turn it slow- 
ly, thus winding the wire upon it. 

The angle between the tube and 
the wire controls the distance be- 
tween the convolutions; hence this 
should be kept constant during the 
winding of a given spring. 

When the coil is removed it will make a spring somewhat less 
than 2 cm. in diameter and 6 or 8 cm. long. Bend a short hook 
on one end of the coil and one 5 cm. long on the other as shown 
in the cut. This spring should now have about 20 convolutions. 
A piece of No. 30 spring brass wire twisted about the long hook 
will form a convenient index, which may be adjusted to the zero of 
the scale by slipping it up or down. 

In exactly the same manner make a second spring of 21 m. of 

No. 22 wire, winding it upon a tube 16 mm. in diameter; this 

spring will be sensitive to 50 mg. but of less capacity than the 

other. Make a scale pan 5 cm. square of cardboard and string. 

To Read the Scale. 

I. The ej^es must be in such a position that the index covers 
its reflection in the mirror. 

II. Read the division of the profile paper covered by the index 
when the eyes are placed as directed above; it will be well to esti- 
mate to half of the smallest division of the profile paper. 

III. Always adjust the index to the zero of the scale before 
weighing an object, as the length of the spring changes with 
the temperature. 



186 



EXPERIMENTAL PHYSICS. 



As described in Appendix L a longer spring and a mirror scale 
may be used when it is desired to weigh articles too heavy for this 
instrument. 



APPENDIX C. 
Atwood's Machine. 

The most important part of this machine is the wheel. This is 
made of brass, has an axle of steel pointed 
at each end, the points fitting in the ends of 
two screws supported in the frame as shown 
in Figure 41. The wheel is attached to a 
piece of board about 20 cm. square, the cor- 
ners of which are cut out to make room for 
the cord carrying the weights. 

The upright which supports the wheel is 
a piece of 1£ inch pipe 2 m. long, having 
a flange on each end. Just back of this and 
to the right in the cut is shown a piece of £ 
inch pipe, which supports three retort stand 
rings modified as at A, B and C in Figure 
41 ; this is placed in such position that the 
weight will pass through the ring A with- 
out striking it. The weights are of iron, 
•one of them carrying a bent wire which 
is engaged by the detent on the base; a piece 
of embroidery silk will answer for the con- 
necting cord. 

To make the detent, remove the upper 
screw which adjusts the end of the armature 
lever of an ordinary telegraph sounder, and Fig. 41. 

to the end of the lever solder a piece of No. 16 brass wire so that 
it will pass through the hole from which the screw was taken. 
Mount the detent on a small square block, using a triangular block 
to keep it upright, and fasten it to the base of the machine in a 
suitable place. The length of the wire attached to the armature 
lever of the sounder is adjusted so that it will engage the hook on 




CONSTRUCTION OF APPARATUS. 187 

the weight when no current is flowing, but will release it when 
the circuit is closed. The pendulum and mercury contact used 
in Exp. 50 are used with this instrument, and distances are 
measured with a meter stick, or with a mirror scale clamped to 
the 1£ inch pipe. 

The shape of the over weights is shown at D; the light ones are 
made of No. 22 sheet brass and the heavy ones of No. 16. 

APPENDIX D. 
The Wide Board. 

A board 50 cm. wide and 2 m. high is used in many experi- 
ments; it is held against the edge of the table by two screws shown 
in Fig. 54. Five holes about 2 cm. in diameter are bored 10 cm. 
apart, in a row across the top of the board, and six more 15 cm. 
apart near one edge. Strips of wood about 2 cm. square nailed 
to the floor on either side of the board will hold the bottom in 
place when this is required. 

APPENDIX E. 
A Spirit Level. 

A cheap spirit level and one which will answer the purposes of 
this course is sold by hardware dealers for about twenty-five 
cents; the tube is enclosed in the iron case, so arranged that it 
may be attached to a steel square. Instead of the square a 
straight edge of hard wood about 3 x 8 x 50 cm. may be used. If 
the ends are exactly at right angles to the sides the level tube may 
be attached to them and used instead of a thumb line. 

APPENDIX F. 

The apparatus required for Exp. 39 consists of two parts, 
(a) A tin tube enclosing a tube of brass or other metal 50 cm. 
long, the expansion of which is to be measured ; and (b) a rack 
which shall support the tube and which carries a micrometer 
screw by means of which the expansion may be measured. 

A. The tinsmith will furnish a 
piece of tin conductor pipe about j 
5 cm. in diameter and 50 cm. 
long. Fig. 42. 



188 EXPERIMENTAL PHYSICS. 

In the middle solder a piece of tin or brass tubing 2 cm. iD 
diameter and 5 cm. long, through which a thermometer may be 
introduced, and at each end solder tubes about 5 mm. in diame- 
ter for the admission and escape of steam as shown in Fig. 42. 

Cut two disks of tin which will just slip into the pipe; bore a 
hole in the centre of each the size of the brass tube. 

Solder these disks to the ends of the conductor pipe and drop- 
ping the brass tubes through the holes bored for the purpose 
solder it there. The brass tube must not project more than 1 mm. 
beyond the tin casing, indeed it should be flush. Solder a thin 
sheet of brass over each end of the brass tube. 

B. Nail two uprights c and d, having a V shaped piece cut out 
of the top, to a board 80 cm. long by about 20 cm. wide in suit- 
able positions to support the apparatus described above. In up- 

a 1. ''4 



Fig. 43. 
right D drive a nail against which the escape tube must always 
press when a measurement is made. (Why?) Solder a piece of 
sheet brass in the slot of a slim two-inch iron screw to make a 
thumb-screw of it; file the other end to a point and insert it in the 
upright at the proper height to strike the brass tube. The expan- 
sion of the bar is measured by means of a simple micrometer 
screw. Obtain from a machinist a screw about T \ of an inch in 
diameter and three inches long, the thread having forty turns to 
the inch. File one end to a point and solder a brass disk 5 cm. 
in diameter to the other. Divide the circumference of the head 
of the screw into 25 parts and etch the divisions and the numbers 
at every fifth mark on the head with nitric acid. Bore a hole 
slightly smaller than the screw through upright b in the proper 
place and insert the screw, turning it slowly and making sure 
that it cuts its own thread in the wood; this construction is neces- 



CONSTRUCTION OF APPARATUS. 189 

sary ; the elasticity of the wood prevents the ' ' lost motion " which 
would make our measurements unreliable if metal were used in- 
stead of wood for the support b, or for the part of it through 
which the screw passes. 

It is obvious that one division of the screw head is equal to .001 
inch and careful work will enable the student to estimate fractions 
of one division. 

APPENDIX G. 

Calorimeter. 

The nickel-plated vessels sold by the hardware dealers as lem- 
onade shakers make good calorimeters; accurate results may be 
obtained, however, with half pound baking powder cans, if the 
joints be resoldered and the surface brightly polished. 

APPENDIX H. 

To Prepare Smoked Paper. 

Cut a sheet of legal cap lengthwise into about four strips, place 
«, lump of camphor gum on a bit of tin, ignite it and move the 
paper back and forth through the flame. 

APPENDIX I. 

A Mercury Contact. 

A block about 1 x 5 x 5 cm. has a hole 3 mm. in diameter bored 
across the grain from one edge to the other. A f inch round- 
headed screw (not shown in the cut) with a copper washer on it 
closes one end of this hole and a 1£ inch 
screw having a piece of sheet brass 
soldered in the slot closes the other end. < 
Fig. 44. A small hole is now bored half 
way through the block, intersecting the Fig. 44. 

ifirst hole. The holes are now filled with mercury. The screw at 
ithe back serves as a binding post for the battery wires. The ele- 
vation of the mercury globule can be controlled by turning the 
thumb-screw shown. 




190 



EXPERIMENTAL PHYSICS. 



The contact above described is very similar, to the one seen in 
the Physical Laboratory of the University of Michigan. 

APPENDIX J. 
Electrical Instruments. 
I. The Bichromate Battery. 

It is desirable that the battery used in these experiments shall 
require only a small amount of fluid, that it shall yield a power- 
ful and nearly constant current, that it shall be cheap. Any form 
of constant battery may be used, but when new cells must be pro- 
vided the author recommends the following; two large tumblers 
serve as battery jars, 4 carbon plates about l x 5 x 10 cm., and 2 
pieces of zinc the same size are required. Four strips of cherry 
£ x 2 x 25 cm. are used to separate the plates. Place a zinc be- 
tween two carbon plates and clamp the whole together as shown 
in Fig. 45 with the clamps used in Exp. 30. The contact with 




Fig. 45. 
the plates is made by soldering a wire to the end of a piece of thin 
sheet copper which is placed beside the zinc plates, and to the mid- 
dle of a piece which is bent and slipped down beside the carbon 
plates. 

A Daniel cell may be easily constructed, if the zinc is a cleft 
cylinder. Cut a strip from a sheet of copper; bend it into cylin- 
drical form, and place it in the porous cup; the basket which 
holds the crystals of copper sulphate may be made by forming a 
piece of copper wire gauze to fit the inside of the cylinder, or 



CONSTRUCTION OF APPARATUS. 



191 



the copper sulphate may be tied in a piece of thin muslin, and 
suspended near the top of the solution; this may also be done when 
the zinc plate is in the porous cup. For the construction of a 
Clark standard cell see Stewart and Gee's Practical Physics, p. 481. 

II. The Tangent Galvanometer. 

Have a reel 30 cm. in diameter and 3 cm. thick, turned out of 
well-seasoned lumber, the flanges being 1 cm. high and 5 mm. 
wide. The central hole should be turned 
out while the reel is in the lathe: the small 
hole is 2 cm., and the front part 7 cm. in| 
diameter, and 1 cm. deep. Fig. 46. Wind * 
four layers of No. 24 B. and S. cotton- 
covered copper wire on the reel, counting 
the convolutions; on this wind 10 convo- 
lutions of No. 22 wire. A strip of sheet 
copper 3 cm. wide is now tacked over the 
wire with brass nails and the ends are 
folded over at right angles to the reel. 
The reel is fastened to the upright block, 
Fig. 46, with two brass screws and thef 
ends of the three coils are connected with 
the four binding posts as shown. 

Insert a plug 1 cm. long in the back part of the center hole. 
From the thinnest looking-glass to be obtained, cut a disk 1 cm. 
in diameter. Magnetise a piece of watch-spring 10 cm. long and 
break off 1 cm. for the needle. Obtain a brass ferrule or a piece 
of brass tubing 1 cm. long, to fit the hole in the reel; bore a hole 
in the center of this. 

Cut a disk of mica 2 mm. smaller than the inside of this fer- 
rule. Attach a fiber of unspun silk to the glass disk. Melt bees- 
wax on the back of the loooking-glass, fasten it to the center of 
the mica, and attach the needle to the other side of the mica in a 
similar manner. Cut out a very narrow strip of the mica, if it 
strikes the suspending fiber. Now attach the free end of the fiber 
to a wire, and pass it through the hole drilled in the ferrule; when 
the mica swings clear, fasten the fiber with a bit of wax. This 




Fig. 46. 



192 



EXPERIMENTAL PHYSICS. 



ferrule is now placed in the center of the reel, with a piece of 
window-glass over it, the object being to check the vibrations of 
the needle by making the air space in which the needle swings as 
small as possible. 




Fig. 47. 
III. The Scale. 

If the scale and sight shown in Fig. 47 be used to read the 
galvanometer, it will not be necessary either to darken the room, 
or to use a telescope. The object of using a telescope in connection 
with a reflecting galvanometer is to determine the line of sight. 
The same end may be accomplished with a device resembling a 
surveyor's compass sights somewhat modified to meet the require- 
ments of the case. A vertical line made on the reel of the gal- 
vanometer just below the mirror determines one point in the line 
of sight; the second point is determined by the wire stretched 
across the opening cut in the upright just above the scale (a 
meter stick), Fig. 47. 

To Set up the Galvanometer. 

Set the galvanometer in the magnetic meridian, set the scale 
60 or 80 cm. away. A piece of looking-glass about 2 cm. square 
may now be attached to the back of the 7 cm. recess about the 
needle with wax. Sighting from one end of the scale, move the 



CONSTRUCTION OF APPARATUS. 



193 



standard so that the other end appears in the mirror just beneath 
the mark which determines the line of sight. 

The scale will now be parallel to the face of the galvanometer, 
and if the center of the scale was previously adjusted to the plane 
of the vertical wire, the line of sight will be at right angles to the 
scale. Fasten both galvanometer and scale in the positions thus 
determined. The eye should be placed back of the wire as the scale 
■can be easily read, say half meter or more; from this position one 
sees the lower part of the wire covering the mark on the galva- 
nometer and just above it the scale moving beneath the wire as the 
needle swings. 



Fig. 48. 

IV. The Bheocord and Bridge. 

A board 3 x 10 x 125 cm. is planed smooth; 8 cm. from one end 
a hole (1) Fig. 48 about 1 cm. in diameter and 1 cm. deep is bored. 
With this hole as a centre strike a circle with a radius of 5 cm., 
boring similar holes at the points 2, 3 and 4. These holes serve as 
mercury cups, and are connected by a link made of heavy copper 
wire, shown beside the instrument in Fig. 50. A strip of sheet cop_ 
per about 1 mm. thick, 15 mm. wide and 5 cm. long is narrowed at 
one end for 1 cm. and the narrow portion bent 
down (Fig. 49) so as to make contact with the * 
mercury in the cup. This is placed in the 
position shpwn in Fig. 48, the binding post Fig, 49. 

A securing it. 

A similar strip of copper is placed in the mercury cup 2, a 
somewhat shorter one in 3, and a longer one in 4. By the side of 
the latter, but not in contact with it, place strip 6, which is about 
15 cm. long, each of them being fastened to the base with brass 
screws and having holes drilled for binding posts at the points 
shown in Fig. 50. Secure a meter stick in the position shown in 



194 



EXPERIMENTAL PHYSICS. 



Fig. 48 and fasten copper strip 5, exactly 1 m. from the ends of 6 
and 7. 




Fig. 50. 

Remove the insulation 'from 210 cm. of No. 30 G. S. wire, by- 
boiling it in caustic soda. Cut the G. S. wire in two in the middle 
and solder one piece to strips 5 and 6, and the other to strips 5 and 
7. Cut a piece of the same size G. S. wire 201 cm. long, double 
it, and beginning at the bend, wind it on an ordinary spool, solder- 
ing i cm. of one end to strip 7 and an equal length of the other 
end to the strip connected with mercury cup 3. In a similar 
manner wind 4 m. of the same wire on a second spool, allowing 5 
mm. on each end for soldering, and being careful to use just this 
amount. The ends of this coil are connected with mercury cups 
2 and 3 respectively. The spools are held in place by long 
brass screws passing through the centre. The slider consists of a 
block 2 x 8 x 10 cm. cut out so that it will slide on the meter stick; 
a 2 cm. hole bored through it just over the meter stick enables its 
position to be located exactly; a saw cut from this hole to the 
front of the block serves to guide the contact springs and a piece 
of sheet brass on the front of the block prevents its striking the 
wires. At the back the binding post E is attached to a copper- 
plate to which are soldered two pieces of copper bent twice at 
right angles, so that in their normal position they do not touch 
the wires beneath them, and that by pressing either down con- 
tact may be made with the wires at will. The instrument may 
be used as a rheocord enabling a gradual resistance to be inserted 
up to that of the 8 m. of wire. When used for this purpose a 
weight say 200 g. placed on the slider will make contact with both 
wires and with the link in cups 1 and 4; the resistance may be 



CONSTRUCTION OF APPARATUS. 



195 



gradually increased until 2 m. of the wire is in circuit. Shifting the 
link to cups 1 and 3, and beginning again at the right with the 
slider we can increase the resistance to 4 m. ; inserting the 4 m. coil 
in circuit and short circuiting the 2 m. coil with a second link we 
may increase it to 6 m. ; and removing the short circuiting link 
we may get the full capacity of the instrument, As described in 
Exp. 67 the rheostat may be used as a Wheatstone bridge, 
and if the resistance of the spools is known, may be used to de- 
termine the resistance in ohms. 




Fig. 51. 

V. The Commutator. 

In a block of wood 2 by 8 by 8 cm. bore four holes 1 cm. deep 
at the corners of the square 3 cm. on the side, — these are mercury 
cups — strips of wood 3 or 4 mm. thick are fastened to either end 
as shown in Fig. 51 and serve to hold the wires in place. A 
short piece of the wire to be connected with a given cup is bent 
at right angles and inserted in the mercury as at A, and is there 
slipped beneath the holding strip as shown at B. The instru- 
ments to be reversed must have their wires connected with diagon- 
ally opposite cups — under these conditions it is evident that turn- 
ing E around 90° will reverse the current in the instrument con- 
nected with the commutator. 

VI. The Spools of Wire. 




Fig. 52. 
The arrangement of the wire used in Exps. 67, 68 and 69 on 
spools as shown in Fig. 52 will prevent the great waste of wire 



196 EXPERIMENTAL PHYSICS. 

which results when students are allowed to cut wire from the 
coils. The wire is doubled and wound on the spool, beginning at 
the bend. If a small hole is bored in the upper part of the spool 
the end of the wire may be thrust into it or wedged in it, and if 
two holes be bored through the opposite end of the spool for the 
free ends of the wire the coils will keep their shape. A brass 
screw fastens the spools to a base. The manner of connecting the 
spools with the binding post is clearly shown in the figure. The 
set of spools shown are wound with the following lengths of wire: 
1. 8 m. No. 18. 2. 8 m. No. 24. 3. 8 m. No. 30. 4. 8 m. No. 
36. 5. 4 m. No. 30. 6. 2 m. No. 30. 

Any desired spool may be placed in circuit by connecting with 
the binding-post between which the spool stands. The wires 
used in Exp. 69 should be similarly mounted. 

VII. Voltameter. 

A simple and satisfactory voltameter, Fig. 53, may be con- 
structed as follows: 

The anode and cathode consist of flat spirals of No. 18 copper 
wire, supported horizontally about 1.5 cm. apart, 
in a tumbler containing a solution of copper sul- 
phate; the length of wire required for each is 75 l 
om., 50 cm. of which is coiled up to form the 
spiral, the end being bent at right angles to its 
plane, and also at the top of the tumbler in such 
a manner as to clasp the edge; a heavy rubber Fig. 53. 
band is now placed around the top of the tumbler over the wires 
to hold them in place. The free ends of the wires serve to con- 
nect with other instruments. 




CONSTRUCTION OF APPARATUS. 



197 



APPENDIX K. 

The Wide Board and Long 
Spring. 

As directed in Appendix B, wind on the 
tube 15 mm. in diameter about 4 m. of No. 
25 spring brass wire, shape the ends as di- 
rected, and suspend the spring from a 
double-pointed tack driven in one of the 
pegs in the wide board. Clamp a mirror 
scale to the wide board in a suitable posi- 
tion. The modulus of this spring should 
be determined as in Exp. 3. 

Fig. 54 shows the arrangement. If a 
small scale-pan is made and attached to a 
heavier spring this device may be used in- 
stead of the platform balance required in 
Exps. 43-5. 




198 



EXPERIMENTAL PHYSICS. 



APPENDIX L. 
A Simple Duprez Galvanomer. 

The tangent galvanometer described in Appendix J, is a very 
satisfactory one to use and gives 
more accurate results than many ex- 
pensive instruments, but the instru- 
ment about to be described is better 
except that for a certain class of work 
a shunt must be employed. 

It is perfectly "dead beat" and 
the deflection is proportional to the 
current. 

The case is made of wood 1 cm. 
thick, except the top piece which is 
2 cm. thick. It is 20 cm. high, 5 cm. 
deep, and 7 cm. wide, inside measure, 
and is put together with brass screws. 

The magnet consists of 10 pieces of 
clock spring £ inch wide, secured in I 
place with small brass bolts. In the 
space between the poles of the mag 
net the field is rendered uniform by the presence of a piece of gas 
pipe, 2£ cm. in diameter and 4 cm. long, turned smooth and 
bored out. 

This is secured to the back of the case with brass machine 
screws, a suitable block being placed back of it, to bring its center 
exactly in the center of the field. 

The coil is wound on a form, 1, Fig. 56, made of three pieces 
of wood, the dimensions of the middle one being s \ 28 I 4;J mm. 
No. 40 silk-covered copper wire is wound on this, making the 
coil about 2 mm. thick. A coat of shellac is applied every layer 
or two, and before taking the wire from the form it is thoroughly 
dried in an oven, or in the upper part of the double boiler used 
in Exp. 45. 

The ends of the coil are soldered to two brass hooks, shown at 
2, Fig. 56, which are bound to the coil with silk beneath pieces of 




CONSTRUCTION OF APPARATUS. 



199 



mica or cardboard, as shown at 3. A piece of thin looking-glass is 
attached to one of the hooks and the coil is suspended in place 
with pieces of the same wire used for the coil, the insulation being 
removed and the wire hardened by drawing it through the fin- 
gers a few times. The lower wire is attached to the spring 
shown on the base of the instrument in Fig 55, and the upper 
end to the hooked wire which serves to bring the coil to the zero. 
A piece of thin window-glass covers the front. 



2 
9 





Fig. 56. 



APPENDIX M. 

Laws of Spiral SpriDgs. 

An interesting alternate for the experiments in elasticity may 
be performed with the apparatus described in Appendix JB. 

Part One. 

Directions. — 1. Using No. 20 brass wire wind two springs on 
the 1 cm. tube. 

By paying a little attention to the angle between the tin tube 
and the wire, you will be able to make two springs having the 
same diameter and the same number of convolutions but of differ- 
ent lengths. Bend hooks on the end of each spring and attach an 
index as in the spring balance. .Suspend each spring from the 
balance frame and determine the elongations by 20 grams. 
Repeat using 50 grams. 

Write the relation which exists between the length of the spring 
and the elongation produced by a given weight. 



200 EXPERIMENTAL PHYSICS. 

Part Two. 

Make three springs having the s-ime number of convolutions 
but varying the diameter of the coil. Determine the elongation 
produced in each of twenty grams. 

Part Three. 

Wind a spring having about 40 convolutions, determine its 
elongation per gram, then cut it in two making one spring with 
10 convolutions and one with 20; determine the elongation as be- 
fore. 

Write the laws proven. 



* THE SCHOOL BULLETIN PUBLICATIONS. « 

Teachers' Question Books. 

1. The Regents' 1 Questions in Arithmetic, Geography, Grammar and Spell- 
ing from the first examination in 1866 to June 1882. (No questions of later date 
will be printed.) Being the 11,000 Questions for the preliminary examinations 
for admission to the University of the State of New York, prepared by the 
Regents of the University, and participated in simultaneously by more than 
250 academies, forming a basis for the distribution of more than a million of 
dollars. Complete tvith Key. Cloth, 16mo, pp. 473. $2.00. 

2. Complete. The same as above but without answers. Pp. 340. $1.00. 
In the subjects named, no other Question Book can compare with this 

either in completeness, in excellence, or in popularity. By Legislative Enact- 
ment no lawyer can be admitted to the bar in the State of New York without 
passing a Regents' Examination in these subjects. 

3. The Dime Question Books, with full answers, notes, queries, etc. Paper, 
pp. about 40. By A. P. Southwick. Each 10 cts. 

Elementary Series. Advanced Series. 

3. Physiology. 1. Physics. 

4, Theory and Practice. 2. General Literature, 
6. U. S. History and Civil Gov't. 5. General History. 

10. Algebra. 7. Astronomy. 

13. American Literature. 8. Mythology. 

14. Grammar. 9. Rhetoric. 

15. Orthography and Etymology. 11. Botany. 

18. Arithmetic. 12. Zoology. 

19. Physical and Political Geog. 16. Chemistry. 

20. Reading and Punctuation. 17. Geology. 

These 10 in one book. Cloth, $1.00. These 10 in one book. Cloth, $1.00. 

Extra Volume, 21. Temperance Physiology. 

The immense sale of the Regents' Questions in Arithmetic, Geography, 
Grammar, and Spelling has led to frequent inquiry for the questions in the 
Advanced Examinations. As it is not permitted to reprint these, we have had 
prepared this series, by which the teacher need purchase books only on the 
subjects upon which special help is needed. Frequently a $1.50 book is 
bought for the sake of a few questions in a single study. Here, the studies 
may be taken up one at a time, a special advantage in New York, since appli- 
cants for Slate Certificates may noio present themselves for examination in only 
part of the subjects, and receive partial Certificates to be exchanged for full Cer- 
tificates when all the branches have been passed. The same plan is very gener- 
ally pursued by county superintendents and commissioners who are encour- 
ing their teachers to prepare themselves for higher certificates. 

It. Quizzism. Quirks and Quibbles from Queer Quarters. Being a Melange 
of questions in Literature, Science, History, Biography, Mythology, Philolo- 
gy, Geography, etc. By A. P. Southwick. 16mo, pp. 55. 25 cts. Key, $1.00. 

A stimulus for home study, and invaluable for school or teachers' 
gatherings. 

5. New York State Examination Questions. Cloth, 16mo, pp. 256. 50 cts. 
This contains all the questions given at all the New York Examinations 

for State Certificates from the beginning. There are more questions and in 
greater variety than in any other collection. It does not give answers. 

6. Tlie Common School Question Book. By Asa L. Craig. Cloth, 12 mo, 
pp. 340. $1.50. We can also furnish Shaw's National Question Book, pp. 351, 
$1.50 ; Stillwell's Practical Question Book. pp. 400, $1.50 ; Brown's Common 
School Examiner, pp. 371, $1.00; Thompson's Teacher's Examiner, pp. 378 
$1.50; Sherrill's Normal Question Book, pp. 460, $1.50. 

N C. W. BAKDEEJf, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Helps toward Correct Speech. 

1. Verbal Pitfalls: a manual of 1500 words commonly misused. Includ- 
ing all those the use of which in any sense has been questioned by Dean 
Alvord, G. W. Moon, Fitzedward Hall, Archbishop Trench, Win. C. H<»dg- 
son, W. L. Blackley, G. F. Graham, Richard Grant White. M. Scheie de 
Wm. Mathews, " Alfred Ayres, M and many others. Arranged alphabetically, 
with 3000 references and quotations, and the ruling of the dictionaries. 
By C. W. Bardeen. 16mo, cloth, pp. 223. 75 cts. 

Perhaps the happiest feature of the book is its interesting form. Some 
hundreds of anecdotes have been gathered to illustrate the various points 
made. These have the advantage not only of making the work entertain- 
ing, but of fixing the point in the mind as a mere precept could not do. The 
type indicates at a glance whether the use of a word is (1) indefensible, <2> 
defensible but objectionable, or (3) thoroughly authorized. 

2. A System of Rhetoric. By C. W. Bardeen. l&no, half leather, pp. 
S13. $1.75. 

3. A Shorter Course in Rhetoric. By C. W. Bardeen. 12mo, half leather,, 
pp. 311. $1.00. 

A. Outlines of Sentence Making. By C. W. Bardeen. 12mo, cloth, pp. 
187. 75 cts. 

5. Practical Phonics. A comprehensive study of Pronunciation, form- 
ing a complete guide to the study of elementary sounds of the English Lan- 
guage, and containing 3,000 words of difficult pronunciation, with diacrui 
cal marks according to Webster's Dictionary. By E. V. De Graff. 16mo. 
cloth, pp. 108. 75 cts. 

The book before us is the latest, and in many respects the best, of the 
manuals prepared for this purpose. The directions for teaching eleinentarv 
sounds are remarkably explicit and simple, and the diacritical mark a are 
fuller than in any other book we know of, the obscure vowels being mai kcd . 
as well as the accented ones. This manual is not like others of the kind, a 
simple reference book. It is meant for careful study and drill, and is es- 
pecially adapted to class use.— Xew England Journal of Education. 

6. Pocket Pronunciation Book, containing 1 the 3,000 words of difficult 
pronunciation, with diacritical marks according to Webster's Dictionary. 
By E. V. De Graff. 16mo, manilla, pp. 47. 15 cts. 

Every vowel that can possibly be mispronounced is guarded by danger 
signals which send one back to the phonic chart for instructions We an* 
glad to notice that the Professor is leading a campaign against the <!• 
ers of the vowel u ; he cannot hold communion with an educated man whose 
third day in the week is "Toosday."— Northern Christian Advocate. 

7. Studies in Articulation • a study and drill-book in the Alphabetic Ele- 
ments of the English language. Fifth thousand. By J. H. Hoose. 16mo, 
cloth, pp. 70. 50 cts. 

This work not only analyzes each sound in the language, but gives as 
illustrations hundreds of words commonly mispronounced. 

Dr. Hoose's M Studies in Articulation " is the most useful manual of the 
kind that I know of. It should bo a text-book in every Teachers' Institute. 
—A. J. Rickoff, formerly BtopH qf School* at Cleveland and at Youker*. 

8. Hints on Teaching Orthoepy. Bv Cms, T. Pooler. 16mo, paper, pp. 
15. 10 cts. 

9. Question Book of Orthography. Orthoepy, and Etymology^ with Notes,. 
Queries, etc. By Albert P. Southwick. 16mo, paper, pp. 40, 10 jts 

10. Question Book of Reading and Punctuation, with Notes, Queries, etc. 
By Albert P. Southwick. lGmo, paper, pp. 38. 10 cts. 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Helps in Language Teaching. 

1. Normal Language Lessons : being the instruction in Grammar given 
at the Cortland State Normal School. By Prof. S. J. Sornberger. 16mo, 
boards, pp. 81. 50 cts. 

Whatever text-book the teacher uses, or if he uses no text-book at all, 
he will find this manual of great assistance. Its classification is simple, Its 
definitions are careful, its tabular analyses are complete, and Us reference by 
page to all the best autlwrs makes it invaluable. 

2. Exercises in English Syntax. By A. G. Bugbee. 16mo, leatherette, 
pp. 87. 35 cts. 

This differs from other handbooks of sentences for class-drill in that it 
does not print wrong sentences to be corrected,— a practice now geuerally 
condemned, because incorrect forms should never be put before the child's 
eye,— but leaves blanks in the sentence to be filled by the pupil from a 
choice of expressions given 2 thus calling in the most effective way to right 
usage and its reasons. It is of especial assistance in preparation for Re- 
gents' examinations, which always include much work of this kind. Send 
for special circular with specimen sentences, and recommendations. 

S. The Begents' Questions in Grammar, from the beginning to June, 
1882. By Daniel J. Pratt, Assistant Secretary. 16mo, manilla, pp. 109. 
25 cts. 

This unequalled series of questions is recognized throughout the country 
as the best drill-book ever made, and the only satisfactory preparation for 
examination. 

An edition of these Questions, with complete answers, and references to the 
grammars of Brown, Murray, Greene, Clark, Kerl, Quackenbos, Weld & 
Quackenbos, Hart, Fowler, Swinton, Reed & Kellogg, and Whitney, will be 
sent post-paid to any address on receipt of One Dollar. It contains 198 
pages, and is handsomely bound in cloth. 

h. Dime Question Boole No. lh, Grammar. By Albert P. Southwick. 
16mo, paper, pp. 35. 10 cts. 

This is one of the best books in a deservedly popular series, giving full 
answers to every question, with notes, queries, etc. Conductor John Ken- 
nedy says: "The bad question book fosters cram; the good one suggests 
study. Mr. Southwick's system is good. It is happy and nourishing. I 
hope you may sell a million of them." 

5. The Diacritical Speller. A practical course of exercises in Spelling 
and Pronunciation. By C. R. Bales. 8vo, boards, pp. 68. 50 cts. 

This work is novel even in a field so thoroughly worked as spelling. Its 
striking features are conciseness and simplicity. The pupil is not drilled 
upon what all pupils know, but only upon what most pupils fail in. The 
collections of words are made with great skin, and the pupil who uses this 
book is not likely to say Toosday or Reuler. The selection of test-words is 
particularly happy, and the exercises in synonyms will afford material for 
many a spare ten minutes.— California Teacher. 

6. An Aid to English Grammar; designed principally for Teachers. 
By Asher P. Starkweather. 16mo, boards, pp. 230. 75 cts. 

This is a grammar aid book on a wholly original plan. It is simply a 
collection of words which are used as two or more parts of speech, with, 
iUustrative sentences to show their correct use. — School Herald, Chicago. 

C. W. BAEDEEN, Publisher, Syracuse, K. Y. 



TUB HCHOOL BULLETIN PUBLICATIONS. 

Helps in Teaching Literature. 

1. A Series of Questions in English and American Literature, prepared 
for class drill and private study by Maky F. Hendrick, teacher in the State 
Normal School, Cortland, N. Y. 16mo, boards, pages 100, interleaved. 35 cts. 

This edition is especially prepared for taking notes ia the literature 
class, and may be used in connection with any text-book or under any in- 
struction. 

2. Early English Literature, from the Lay of Beowulf to Edmund Spen- 
ser. By Wm. B. Harlow, instructor in the High School, Syracuse, N. Y. 
16mo, cloth, pp. 138. 75 cts. 

This handsome volume gives copious extracts from all leading authors, 
of sufficient length to afford a fair taste of their style, while its biographical 
and critical notes give it rare value. 

3. Dime Question Book No. 2, General Literatim, and No. IS, America* 
Literature. By Albert P. Southwick. 16mo, paper, pp. 35, 39. 10 cts. each. 

These are among the most interesting books in the series, almunding in 
allusion and suggestion, as well as giving full answers to every question. 
They afford a capital drill, and should be used in every class as a prepara- 
tion for examination. 

U. Hoiv to Obtain the Greatest Value from a Bool. By the Rev. K. W. 
Lowrie. 8vo, pp. 12. 25 cts. 

No one can read this essay without pleasure and profit. 

5. The Art of Questioning. By Joshua G. Fitch. 16mo, paper, pp. K. 
15 cts. 

Mr. Fitch, one of Her Majesty's inspectors of schools, now recognized as 
the ablest of English writers on education, owed his early reputation to thw 
address, the practical helpfulness of which is everywhere acknowledged. 

6. The Art of Securing Attention. Bv Joshua G. Fitch. lGino, paper, 
pp. 43. 15 cts. 

The Maryland School Journal well says: " It is itself an exemplification 
of the problem discussed, for the first page fixes the attention so that the 
reader never wearies, till he comes to the last and then wishes that the end 
had not come so soon." 

7. Tlie Elocutionist's Annual, comprising new and popular Readings, 
Recitations, Declamations, Dialogues, Tableaux, etc., etc. compiled oy 
Mrs. J. W. Shoemaker. Paper, lomo, pp. 200. Vt Numbers. Price of each, 

30 cts. 

Though primarily designed for classes in elocution, the character of the 
selections is so high that any of these volumes may be used with profit in a 
literature class. 

8. The BIN* in the Public School". Paper, Mmo, 8 vol-., pp. 214, 228. 
50 cts. 

These volumes contain the most important arguments, decisions, and 
addresses connected with the celebrated contest in Cincinnati, 1W09. 

C. W. BARDEEN, Publisher, Syracuse, X. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. ■ 

Books for Young Teachers. 

1. Common School Law for Common School Teachers. A digest of the 
provisions of statute and common law as to the relations of the Teacher to 
the Pupil, the Parent, and the District. With 500 references to legal decis- 
ions in 28 different States. 14th edition, wholly re- written, with references 
to the Code of 1888. By C. W. Bahdeen. 16mo, cloth, pp. 120. Price 75 cts. 

The reason why the teacher should make this his first purchase is that 
without a knowledge of his duties and his rights under the law he may fail 
either in securing a school, in managing it, or in drawing the pay for his ser- 
vices. The statute provisions are remarkably simple and uniform. 7ihe de- 
cisions of the Courts, except upon two points, here fully discussed, follow 
certain defined precedents. An hour to each of the eleven chapters of this 
little book will make the teacher master of any legal difficulties that may 
arise, while ignorance of it puts him at the mercy of a rebellious pupil, an 
exacting parent, or a dishonest trustee. 

2. Hand-BooJcfor Young Teachers. By H. B. Buckram, late principal of 
the State Normal School at Buffalo. Cloth, 16mo, pp. 152. Price 75 cts. 

It anticipates all the difficulties likely to be encountered, and gives the 
l»eginner the counsel of an older friend. 

8. The School Room Guide, embodying the instruction given by the author 
at Teachers' Institutes in New York and other States, and especially in- 
tended to assist Public School Teachers in the Practical Work of the School- 
Room. By E. V. DeGraff. Thirteenth edition, with many additions and 
corrections. 16mo, cloth, pp. 398. Price $1.50. 

As distinguished from others of the modern standards, this is a book of 
Methods instead of theories. It tells the teacher just what to do and how to 
do it ; and it has proved more practically helpful in the school-room than 
any other book ever issued. 

h. A Quiz-Book on the Theory and Practice of Teaching. By A. P. 
Southwick, author of the "Dime Question Books." 12mo, pp. 220. Price $1.00. 

This is one of the six books recommended by the State Department for 
study in preparation for State Certificates. The others are Hoose's Methods 
(f 1.00), Hughes's Mistakes (50 cts.), Pitch's Lectures ($1.00), Page's Theory and 
Practice ($1.25), and Swett's Methods ($1.25). We will send the six post-paid 
for $5.00. 

5. Mistakes in Teaching. By James L. Hughes. American edition, with 
contents and index. Cloth, 16mo, pp. 135. Price 50 cts. 

More than 15,000 have been used in the county institutes of Iowa, and 
elsewhere superintendents often choose this book for their less thoughtful 
teachers, assured that its pungent style and chatty treatment will arrest- 
attention and produce good results. 

6 How to Secure and Retain Attention. By James L. Hughes. 16mo, 
eloth, pp. 97. Price 50 cts. 

This touches attractively and helpfully upon the first serious difficulty 
the teacher encounters. No young teacher should neglect these hints. 

7. Primary Helps. A Kindergarten Manual for Public School Teachers. 
By W. N. Hailmann. 8vo, boards, pp. 58, with 15 full-page plates. Price 75 cts. 

In these days, no primary teacher can afford to be ignorant ©f " The New 
Education," and this is perhaps the only volume that makes kindergarten 
principles practically available in public schools. 

8. Dime Question Book, No. 4, Theory and Practice of Teaching. 16mo, 
paper, pp. 40. Price 10 cts. By A. P. Southwick. 

A capital preparation for examination. 
C. W. BARDEEN, Publisher, Syracuse, N, Y. 



THE SCHOOL BULLETIN PUBLICA 'l ."s.XS. 

The Five Great English Books. 

.The recognition of Teaching as a Science was much earlier In England 
than in this country', and the five books which are there recognized as stan- 
dards, have probably no equals in soundness and scope. Hence they are 
usually the first books adopted by Reading Circles, and are indispensable to 
the library of an intelligent teacher. These are : 

1. Essays on Educational Reformers. By Robert Henry Quick. Cloth, 
16mo, pp. 330. Price $1.50 ; or special edition, thinner covers, price $1.00. 

This is altogether the best History of Education. " With the suggestion 
that study should be made interesting" writes Principal Morgan, of the Rhode 
Island State Normal School, "we most heartily agree. How this may be 
done, the attentive reader will be helped in learning by the study of this 
admirable book." 

2. Lectures on Teaching. By J. G. Fitch. New Edition with a Preface 
by an American Normal Teacher. Cloth, lGmo, pp. 393. Price $1 .25. 

This forms the proper Basis for pedagogical knowledge, beginning with 
the teacher, the school, and the school-room, and giving the why as well as 
the what. YVe publish in our "School Room Classics" the "Art of Ques- 
tioning," and the "Art of Securing Attention," by the same author, at 15 
cents each. 

S. Lectures on the Science and Art of Education. By Joseph Payne 
Cloth, 16mo, pp. 384. Price §1.00. 

The student is now ready to take up the Science of Education, which is 
nowhere else so brilliantly and effectively presented. The lectures are sin- 
gularly fascinating, and the full analysis and indexes in this edition make it 
easy to collate and compare all that the author has uttered upon any topic 
suggested. 

.',. The Philosophy of Education, or the Principles and Practice of 'Patching. 
~By Thomas Tate. Cloth, 16mo, pp. 440. Price $1.50. 

This gives the application of the Science to the Art of Teaching, and is 
without a rival in its clear presentation and abundant illustrations. The 
tuthor is not content with giving directions. He shows by specimens of 
■^ass-work just what should be done and may be done. 

.'. Introductory Text-Book to School Education, Method and School Man- 
agement, By John Gill. Cloth, lGmo, pp. 270. Price $1.00. 

This supplements the work of all the rest by practical directions as to 
School Management. Of the five this has had a sale equal to that of all the 
rest combined. The teacher's greatest difficulty, his surest discomfiture if 
he fails, is in the discipline and management of his school. That this man- 
ual has proved of inestimable help is proved from the fact that the present 
English edition is the 44th thousand printed. 

C. W, BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

The School Room Classics. 

Under the aboye title we have published a series of Monographs upon 
Education, as follows, all 16mo, in paper, at 15 cts. each. 

1. Unconscious Tuition. By Bishop Huntington. Pp. 45. 

" There is probably nothing finer in the whole range of educational lit- 
erature."— Ohio Educational Monthly. 

"It cannot be read without a wholesome self -weighing, and a yearning 
which develops true character." — The Schoolmaster, Chicago. 

2. The Art of Questioning. By J. G. Fitch. Pp. 36. 

"Mr. Fitch is happily inside his subject, and as clear as a bell."— Chris- 
tian Register. 

3. The Philosophy of School Discipline. By John Kennedy. Pp. 23. 
"Clear and logical, and goes down to the very foundation."— Utica 

Herald. 

h. The Art of Securing Attention. By J. G. Fitch. Pp. 43. 

"Perhaps I overestimate Fitch's works, but I fail to find in the state- 
ment of any other educational writer a juster comprehension of the needs 
And difficulties of both teacher and pupil, or more common sense put into 
neater, clearer style."— The Student, Philadelphia. 

5. Learning and Health. By B. W. Bichardson. Pp. 39. 
"A timely topic ably treated."— N. E. Journal of Education. 

" Certainly worth many times its weight in gold."— Eclectic Teacher. 

6. The New Education. By J. M. W. Meiexejohn. Pp. 35. 

" Absolutely the best summary we have seen of the doctrines of Froebel 
in their present development." — N. Y. Sclwol Journal. 

7. A Small Tractate of Education. By John Milton. Pp. 26. 

"Far more important in the literature of the subject than the treatise 
of 'Locked— Encyclopedia Brittanica. 

8. TJie Sclwol Work-Shop. By Baroness von Maeenholz-Buelow. trans- 
lated by Miss Blow, Pp. 27. 

"In this treatise the kindergarten view of Industrial Education receives 
its best exemplification. "— iV. E. Journal of Education. 

9. Sex in Mind and in Education. By Henrt Maudsley. Pp. 42. 
"A masterly treatment of a delicate subject." — N. E. Journal of Edu- 
cation. 

10. Education as Viewed by Thinkers. Pp. 47. 

This contains 95 classified quotations from leading authorities of every 
time and country, and will be of use to every writer and speaker. 

11. How to Teach Natural Science in Public Schools. By Wm. T. Harris. 
Pp. 40. 

Since this was first published in 1871 for the schools of St. Louis, it has 
been regarded as the standard authority upon the subject, and this edition, 
revised by the author, was prepared by the request of the Committee on 
Physics-Teaching in 1887 of the National Association. 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Instruction in Citizenship. 

1. Civil Government for Common Schools, prepared as a manual for 
pubhc instruction in the State of New York. To which are appended the 
Constitution of the State of New York as amended at the election of 1882, 
the Constitution of the United States, and the Declaration of independence, 
etc., etc. By Henry 0. Northam. 16rno, cloth, pp. 185. 75 cts. 

Is it that this book was made because the times demanded it, or that the- 
publication of a book which made the teaching of Civil Government practi- 
cable led to a general desire that it should be taught ? Certain it is that this- 
subject, formerly regarded as a " fi niching " branch in the high school, is 
now found on every teacher's examination-paper, and is commonly taught 
in district schools. Equally certain is it that in the State of New York this, 
text-book is used more than all others combined. 

2. A Chart of Civil Government. By Charles T. Pooler. Sheets l^xl ft, 
5 cts. The same folded, in cloth covers, 25 cts. 

Schools using Northam's Civil Government will find this chart of great 
use, and those not yet ready to introduce a text -book will be able to give no- 
little valuable instruction by the charts alone. Some commissioners have 
purchased them by the hundred and presented one to every school house in 
the county. 

S. Handbook for School Teachers and Trustees. A manual of School 
Law for School Officers, Teachers and Parents in the State of New York. 
By Herbert Brownell. 16mo, leatherette, pp. 64. 35 cts. 

This is a specification of the general subject, presenting clearly, defi- 
nitely, and with references, important questions of School Law. Particular 
attention is called to the chapters treating of schools under visitation of the 
Regents— a topic upon which definite information is often sought for in vain. 

h. Common School Law for Common School Teachers. A digest of the 
provisions of statute and common law as to the relations of the Teacher to 
the Pupil, the Parent, and the District. With 500 references to le^al deci«- 
ionsin 28 different States. 14th edition, whoUy re-written, with referrn<<-s 
to the new Code of 1888. By C. W. Bardeen. 16mo, cloth, pp. 120. 75 cts. 

This has been since 1875 the standard authority upon the teacher's rela- 
tions, and is frequently quoted in legal decisions. The new edition is much 
more complete than its predecessors, containing Topical Table of Content s T 
and a minute Index. 

5. Laics qf New York relating to Common >ScJiools, with comments un-l 
instructions, and a digest of decisions. 8vo, leather, pp. 867. $4.00. 

This is what is known as " The New Code of 1888," and contains all r.>- 
visions of the State school-law to date. 

6. T/ie Powers and Duties of Officers and Teachers. By Albert P. Mar- 
ble. 16mo, paper, pp. 27. 15 cts. 

A vigorous presentation in Sup't Marble's pungent style of tendencies 
as well as facts. 

7. First Principles of Political Economy. By JoxErn Alden. 16mo,. 
cloth, pp. 153. 75 cts. 

Ex-President Andrew IX White says of this book: "It Is clear, well 
arranged, and the best treatise for the purpose I have ever seen." 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



7±/E SCHOOL BULLETIN" PUBLICATIONS. 

Maps, Charts and Globes. 

I. Johnston s Wall Maps These are of three sizes, 27x33 inches, costing 
$2.50 each; 40x48» costing $5.00 each; and 63x72, costing $10.00 each. 

The Common School Series includes (a) Hemispheres, (6) North America, 
(<?) South America , (a') United States, ie) Europe, (/) Asia, (a) Africa. Others 
sometimes substituted or added are (Ji) "World, Mercator's Projection, (i) 
Eastern Hemiphere, (k) Western Hemisphere. 

We can furnish also in the 40x48 size: (I) England, (m) France, (n) Italy, 
(o) Spain, (p) Central America, (q) Orbis Veteribus Notus, (f) Italia Antiqua, 
(s) Graecia J.ntiqua, it) Asia Minor, (u) Orbis Romanus, (ic) De Bello Gallico, 
(x) Canaan and Palestine, (y) Bible Countries, (z) United States, historical, 
showing at a glance when and whence each portion of its territory was de- 
rived—a very valuable map in history classes. 

All these maps are engraved on copper, and printed in permanent oil 
colors. All are cloth-mounted, on rollers. Spring rollers are added at an 
extra cost of $1.00, $1.50, and $2.50 respectively. 

We offer a special consignment of T. Ruddiman Johnston's maps 40x48, 
in sets only., including Hemispheres, North America, South America, United 
States, political, United States, historical, Europe, Asia, and Africa, 8 maps, 
regular price $40.00, at $15.00 per set. They were prepared for a firm in the 
west who have been obliged to discontinue the business, and were sent to 
us by the Johnston Co. with instruction to close them out at once. Hence 
the unparallelled price, which applies ®nly to this 100 sets. 

8. Bulletin Map of the United States. Paper, on rollers, 33^x5 ft., with 
Blanchard's chart of the United States History upon the back. $3.00. 

This is colored both by States and by Counties and gives correctly the 
new time lines. 

h. Map of New York State, colored both by Counties and by Towns, 
2^x3 ft. on rollers. Paper, $1.00; Cloth, $2.00. 

5. Adams's Large Map of New York State, 61x66 inches. Cloth, on rollers, 
$10.00; on spring rollers, $12.00. We >nre now the sole proprietors of this 
latest and best map, and can hereafter fill all orders promptly. 

6. Dissected Map of New York, ss «m into Counties. 75 cts. 

7. Dissected Map of the United States, sawn into States. 75 cts. 

8. Chart of Life Series of Phystclagy Charts, 23x27 inches, four in num- 
ber, including one to show the effecis of alcohol on the system. These show 
every organ, life-size and in place. Per set, $10.00; on spring rollers, $12.50. 

9. EckharVs Anatomical Chart), consisting of 12 double plates, with 
more than 100 distinct and separate figures. Per set, $15.00. 

10. Heading Charts of all kinds. Appleton's, $12.50; Monroe's Complete, 
$10.00. Monroe's Abridged, $6.00, ere. 

The School Bulletin Globe. Whi) e we keep a dozen styles always in stock, 
we recommend this especially becsttse: 1. It is 12 or 6 inches in diameter. 2. 
It has a low and heavy Bronzed Iron Frame. Its axis is adjustable. 4. 
It shows an entire Hemisphere. 5. Its Meridian is movable. 6. Its map is 
Johnston's. 7. It is shipped to an? address at Fifteen Dollars for a 12-inch 
or Five Dollars for 6-inch size. 8. jEvery Globe is guaranteed to be abso 

LUTEEY PERFECT (14) 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Blackboard Material. 

Xo feature of the school-room is of more vital importance to the health 
of scholars and teachers than the Blackboard. If it be pray or greasy the 
amount of chalk used fills the air with dust, which produces catarrhal and 
bronchial difficulties, and yet makes so faint a mark that the children's 
eyes are permanently injured. Choice should be made among the following 
materials. 

1, Solid Slate. This is durable, but costs from 30 to 50 ct3. a square foot, 
is noisy, not black enough in color, and unhealthful because there is com- 
monly used upon it the softest crayon. Where solid slate is already in, we 
recommend the Slate Pencil Crayon, as the only preventive of serious disease. 

But it is better to put either upon the plastered wall, or upon the wall 
covered with manilla paper, or upon wooden boards, one of the following 
preparations. 

2. Agalite Slating. This is the cheapest of all, may be sent by mail, and 
usually gives fair satisfaction. Price, post-paid, for box to cover 400 feet, 
one coat. $6.00; 200 feet, $8 25; 100 feet, $1.73; 50 feet, $1-00. We furnish the 
Black Diamond or Silicate Slating at the same price, but it can be sent only 
by express. 

5. Slate Pencil Slating. This remarkable preparation does away alto- 
gether with chalk-dust, having sufficient grit to take a distinct mark from a 
siate-pencil. Soft crayon, should never be used upon it. unless it is first rubbed 
down to smoother surface. It is a pure alcohol slating, and therefore dura- 
ble. Price per gallon, covering 600 ft., one coat, $10.00; quails, $2.75; pints 
$1.50. 

In many schools using the Slate Pencil Slating, the State Normal at 
Potsdam, for instance, Faber's slate-pencils have taken the place of crayon. 
In other schools hard crayon, like Alpha H, is used. 

h. Hornstone Slating. This is new, and altogether the best in the market, 
making a really stone surface which is yet absolutely Mack. There is no 
waste of chalk, even with soft crayon, while the Alpha II produces a 
beautifully clear mark. It contains no oil or grease, and grows harder with 
age. It is put on with a paint-brush, and adheres to any material, so that 
it may be put on walls, boards, paper, or any other smooth surface. Price 
S'8.00 per gallon, covering 200 feet with/owr coats. It is somewhat expen- 
sive, and must be put on with care; but when properly finished it is a delight 
to the eye. 

Sup't Smith, of Syracuse, says: ''Your Hornstone Slating la now in use 
in four of our buildings, and I have no hesitation in saying that it is superior 
to solid slate or to any other blackboard surface I ever saw."— Principal 
Miner, of Skaneateles, says: " Its very smooth surface saves crayon and les- 
sens the amount of chalk-dust in the room — I do not hesitate to say that 
it is the best board I ever used." 

Cheneys DusUeu Eraser* work well on any of the boards named. 
Price 10 cts. each, $1-00 a dozen. The School Bulletin Erasers are made of 
the closest and best felt, and are verv durable. Price 15 cts. each, $1.50 a 
dozen. Specimen of either by mail for 15 cts. Alpha Crayon, M or 11, 75 
cts. a box. Ordinary W Mis Crayon, 15 cts. a boj yon, 75 cts a 

box. Slate Pencil Crayon, for solid slate, -a) cts. a box. (13) 

C. W. BAUDEEN, Publisher, Syracuse, H. Y. 



—THE SCHOOL BULLETIN PUBLICATIONS.-—- 

School Records and Reports. 

1. The Bulletin Class Register. Designed by Edwakd Smith, Superin- 
tendent of Schools, Syracuse, N. Y. Press- board cover. Three Sizes, (a) 6x7, 
for terms of twenty weeks; (5) 5x7, for terms of fourteen weeks. When not 
otherwise specified this size is always sent. Pp. 48. Each 25 cts. (c), like (b) 
but with one half more (72) pages. Each 35 cts. 

This register gives lines on each of 12 pages for 29 names, and by a nar- 
row leaf puts opposite these names blanks for one entry each day for either 
14 or 20 weeks, as desired, with additional lines for summary, examina- 
tions, and remarks. Nothing can be more simple, compact, and neat, where 
it is desired simply to keep a record of attendance, deportment, and class- 
standing. It is used in nearly two-thirds of the union schools of New York. 

2. The Peabody Class Record, No. 1, with 3 blanks to each scholar each 
day for a year. Boards 4^x9J4 pp. 100, $1.00. No. 2, with 5 blanks to each 
.scholar, 8x11, $1.50. Like No. 1, but gives 3 or 5 blanks each day. 

3. Ryan's School Record, 112 blanks to a sheet, per dozen sheets, 50 cts. 
h. Keller's Monthly Report Card, to be returned with signature of parent 

or guardian, card-board 2%x4, per hundred, $1.00. 

5. Babcock's Excelsior Grading Blanks, manilla, 3x5, with blanks on both 
sides. Comprising (a) Report Cards; (b) Grade Certificates for each of 9 

frades; (c) High School Certificate (double size). Price of (a) and (&) $1.00 a 
undred; of (c) $1.50 a hundred. 

6. Shaw's Scholar's Register, for each Week, with Abstract for the Term. 
Paper, 5x7, pp. 16. Per dozen, 50 cts. Each pupil keeps his own record. 

7. Jackson's Class Record Cards. Per set of 90 white and 10 colored 
cards, with hints, 50 cts. Only imperfect recitations need be marked. 

8. Aids to Sclwol Discipline, containing 80 Certificates, 120 Checks, 200 
Cards, 100 Single and Half Merits. Per box, $1.25. Supplied separately per 
hundred: Half Merits, 15cts., Cards, 15 cts., Checks, 50 cts., Certificates, 50 cts. 

The use of millions of these Aids, with the unqualified approval of teach- 
ers, parents, and pupils, is assurance that they are doing great good. 

They save time by avoiding the drudgery of Eecord keeping and Reports. 

They abolish all notions of "partiality" by determining the pupil's 
standing with mathematical precision. 

They naturally and invariably awaken a lively paternal interest, for the 
pupil takes home with him the witness of his daily conduct and progress. 

They are neat in design, printed in bright colors. The Certificates are 
prizes which children will cherish. The Single Merits and Half Merits are 
printed on heavy card board, the Cards and Checks on heavy paper, and both 
may be used many times— hence the system is cheap, as well as more at- 
tractive than any other to young children. 

9. Mottoes for the School-Room. By A. W. Edson, State Agent of Massa- 
chusetts. Per set of 12 on heavy colored card-board 7x4 inches, printed on 
both sides, $1.00, post-paid, $1.10. 

These mottoes are " Never too Late," "Above all, be Useful," "Dare to 
Say No," " God Bless our School," "Avoid Anger," " Be Good, Do Good," 
" Think, Speak, Act the Truth," "Fear to Do Wrong," "Misspent Time is 
Lost Forever," "Speak the Truth," " Act Well Your Part," "Strive to Ex- 
cel," "Try, Try Again," "Be Diligent, Prompt, and Useful," "Think Good 
Thoughts," " Learn to Study," "Before Pleasure Comes Duty," "Think 
First of Others," " Dare to Do Right," " Order is Heaven's First Law," "A 
Will Makes a Way," "Study to Learn," "Hold Fast to Honor," "God 
Sees Me." (12) 

C, W. BAKDEEN, Publisher, Syracuse, N". Y. 



-THE SCHOOL BULLETIN PUBLIC ATIOXS. - 



Algebra, 


Rhetoric, 


Geology, 


Geometry, 


Literature. 


Botany, 


Drawing, 


History, 


ZoOlogy, 
Physiology, 


Penmanship, 


Latin, 



Official Question Books. 

1. The Neuo York State Examination Questions from the beginning to 
the present date. Cloth, lCmo, pp. 274, 50 cts. 

These annual examinations, only by which can State Certificates be ob- 
tained in New York, have a reputation all over the country for excellence 
and comprehensiveness. The subjects are as follows : 

Arithmetic, Grammar, Physics, Geography, 

Book-Keeping, Composition, Chemistry. Civil Government. 

Astronomy, 
Methods, 
School Economy, 
School Law. 
No answers are published, except in the following special volume. 

2. Dime Question Book on Book- Keeping, containing all the question* in 
that subject given at the first 15 New York Examinations for State Certifi- 
cates, with full Answers, Solutions, and Forms. Paper, 16mo, pp. 31, 10 cts. 

8. The Uniform Examination Questions. By voluntary adoption of the 
113 School-Commissioners of the State of New York, certificates are now 
given only on examinations held under these questions, which are issued 
sealed from the State Department. They are published in the School Bulle- 
tin of the following dates, with Complete Official Answers; price of each, 
10 cts. 

June, 1888, School Law, 31 Questions and Answers. 

July, 1888, Arithmetic, 167 

Aug., 1888, Geography, 385 

Oct., 1888, Grammar, 328 

Nov., 1888, Physiology, 250 

Dec, 1888, Am. History, 301 " " 

k. The Cicil Service Question Book. Cloth, 16mo, pp. 282, 81.50, 
42,000 places are now filled exclusively by appointments dependent on 
examinations. No favoritism is possible. You do not need the influence of 
Congressman or of politician. You have only to learn when the next ex- 
amination is held, apply for the necessary papers, present yourself, and 
answer the questions asked. The appointments are made from those who 
stand highest, and are open to women as well as to men. All the particu- 
lars as to these examinations, the places and dates where held, and how to 
apply, are here given with 943 specimen questions in AHthmetic, 575 specimen 
questions in Geography, 400 specimen questions in English Syntax, 100 each 
in American History and Civil Government, with full treatises on Book-h'^/,- 
ing and on Letter-Writing. To prepare for competition for places at $1,000 
and higher these subjects and tfiese only are required. Any one who can 
answer the questions here given, to all of which fidl and complete answers are 
added, is ready to enter the next examination. 

Hon John B. Riley, Chief Examiner, State of New York. July 10, 1888, 
says : " I am pleased with your Civil Service (Question Book. It will not only 
be of service to those intending: to try the Civil Service examinations, but 
teachers or others who are obliged to prepare questions for examinations in 
the common English branches will find it a great convenience." 

The N. E. Journal of Education says, Aug. 23, 1888 : " It is rarely that any 
book can be found with so many valuable and so few unimportant questions." 
OTHER QUESTION BOOKS. 
5. The Common School Question Book. By Asa L. Craig. Cloth, 12mo, 
pp.340. SI. 50. Shaw's National Question Book, pp. 351, $1.50: Stillwelx's 
Practical Question Book, pp. 400, 8150 "Brown's Common School Examines, 
pp. 371, $1.00 ; Thompson's Teacher's Examiner, pp. 878, $1.50; Sherrill's 
Normal Question Book, pp. 400, $1.50. 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Helps in^Teaching History. 

£ A Thousand Questions in American History. . 16mo, cloth, pp. 247. 
Price $1.00. 

This work has been prepared by an eminent teacher for use in his own 
school— one of the largest in the State. It shows rare breadth of view and 
discrimination, dealing not merely with events but with causes, and with th® 
side-issues that have so much to do with determining the destiny of a nation. 

8. Helps in Fixing the Facts of American History. By Henry C. Noe- 
- 16mo, cloth, pp. 298. Price $1.00. r -< 



Here all facts are presented in groups. The i L— exington. ^ 
key-word to the Revolution, for instance, is [ I— ndependence.\^ 
LIBERTY, as shown in the accompanying table B— urgoyne's Surrender.^ 
of Key- Words ; and in like manner the events of E— vacuation. 
the late civil war are kept chronologically dis- R— etribution. 
tinct by the key-words SLAVES FREED. Chart T— reason, f 
No. 1 indicates by stars the years in each decade Y— orktown. ^ ^ 
from 1492 to 1789, in which the most remarkable events occured, while the, 
colored chart No. 2 arranges the events in twelve groups. 

3. Topics and References in American History, with numerous*Searoh 
■Questions. By Geo. A. Williams. 16mo, leatherette, pp. 50. 50 cts. 

This is a book of immediate practical value to every teacher. The refer- 
ences are largely to the lighter and more interesting illustrations of history, 
of a kind to arouse the thought of pupils by giving vivid conceptions of the 
events narrated. By dividing these references among the members of a class, 
the history recitation may be made the most delightful of the day. 

h. Dime Question Books, No. 5, General History, and No. 6, United States 
History and Civil Government. By Albert P. Southwick. 16mo, paper, pp. 
37, 32. 10 cts. each. 

5. Outlines and Questions in United Slates History. By C. B. Van Wis. 
16mo, paper, pp. 40, and folding Map. 15 cts. 

The outgrowth of four years' practical work in the school-room with 
map prepared by a pupil as a suggestive model. 

6. TabUt of American History, with Map of the United States on the 
back. By Rurus Blanchard. Heavy paper, mounted on rollers, 3^2 by 5 
feet. Price, express paid, $3.00. 

The demand for a colored chart to hang upon the wall and thus catch 
the often-lifted eye of the pupil, has led to the preparation of this chart by 
an experienced author. The events of the four centuries are grouped in 
-parallel belts of different colors, and upon the corners and sides are names 
of the States and Territories, with their etymology, etc., history of political 
parties, portraits of all the Presidents, Coats of Arms of all the States, etc. 
The map is engraved expressly for this chart by Rand & McNally, is colored 
both by States and by counties, and gives all the latest railroads, the new ar- 
rangement of time-lines, showing where the hour changes, etc. 

C, W, BARDEEN,, Publisher, Syracuse, N. Y. 



-THE SCHOOL BULLETIN PUBLICATIONS.- 



Music in the School Room. 

1. The Song Budget. A collections of Songs and Music for Educational 
Gatherings. By E. V. De Graft. Small 4to, paper, pp. 70. 15 cts. 

This book owes its popularity to two causes : 

(1) It gives a great deal for the money. 

(2) The songs are not only numerous (107), but they are the standard faeor- 
itesofthe last fifty years. 

This is why the book contains more music that will be used than any other 
book published. For in all other books that we know of, two-thirds i \t the 
tunes are written by the compilers, who are of course partial to their own 
productions. Sup't De Graff wrote no songs of his own, but gathered th< ee 
which his long experience as a conductor of teachers' institutes had shown 
him to be the most generally familiar and pleasing. 

In fact, the success of this book has been due to the fact that only those 
songs were admitted that have proved to be universal favorites, this in- 
volved a large original outlay, as much as fifty dollars having been paid for 
the right to use a single song. But the best were taken, wherever thev 
could be found and at whatever cost, and the result is a school singing-book 
of popularity unexampled. For instance, a single firm in Cleveland. Ohio, 
J. 11. Holcomb & Co.. had purchased of us up to Feb. 15, 1888, no less than 
0730 copies, 4.500 within the last six months, besides 2100 of the School Com 
Chorus. 

2. The School Boom Chorus. A collection of Two Hundred Soaj 
Public and Private Schools, compiled by E. V. De Graff. Small, 4to. boards. 
pp. 148. 35 cts. 

This is an enlarged edition of the Song Budget, with twice the number 
of songs. The plates of the last edition are so arranged that it is identical 
with the Song Budget as far as page 68. so that both books can be used to- 
gether. The Budget and Chorus are particularly adapted for Teachers' 
<iations and Institutes. At these prices every meeting of teachers can I 
plied with one or the other, while the fact that the tunes arc standard 
favorites makes it easy for any audience to join in the singing at sight 

3. The Diadem of School Songs • containing Songs and Music for all 
grades of Schools, a new svstem of Instruction in the elements of Music, 
and a Manual of Directions for the use of Teachers. By Wm. Tilling 
Small, 4to, boards, pp. 160. 50 cts. 

This book, of which Dr. French, the veteran institute-instructor was 
asso ciate author, gives an exceedingly simple and practical svstem of in- 
struction, as well as a valuable collection of songs. 

h. Half a Hundred Songs, for the School-Room and Home. By Hattik 
S. Russell. 16mo, boards, pp. 103. 

These songs are all original, but without music. 

.". The School Vocalist; containing a thorough svstem of elementary 
instruction in Vocal Music. With Practical Exercises. Songs. Ilvmns. < I 
<fcc, adapted to the use of schools and Academies. By E, Locks, andS. 
Noukse. Oblong, boards, pp. 160. Price 50 cts. 

6. The School Melodist. A song Book for School and Home. By E. 
Locke and s. Noubse. oblong, boards, pp. 100. Price BO ots. 

7. The Song Life, for Sunday Schools, etc., illustrating in song the 
.iourney oi Christiana and her children to the Celestial City, small 4to 
boards, pp. 176. Price 50 cts. 



Nos. 5. 6, and 7 are books that have had their day, but of which we have 
hundred copies of each on hand. These we will sell at 10 cts. each | 



a few 

if to go by mail. 6 cts. each extra. They contain much good music 



C. W. BARDEEX, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Arithmetic by the Grube Method. 

1. First Steps among Figures. A drill book in the Fundamental Rules 
of Arithmetic. By Levi N. Beebe. Cloth, 16mo, 3 editions. Pupils' 1 Edi- 
tion, pp. 140, 45 cts. Oral Edition, pp. 139, 50 cts. Teachers' Edition, includ- 
ing all in both the others, with additional parallel matter, Index, and Key, 
pp. 326, $1.00. 

These books give the only practical exposition of the Grube Method, now 
generally admitted to produce the best results with beginners. It has been 
used ten years in the primary schools of such cities as Norwich, Conn., and 
Auburn, N. Y., and for many years every student in the Albany State Normal 
School has been directed to purchase a copy to take with him for his subse- 
quent use in teaching. 

From a multitude of testimonials we copy the following : 

"We are still successfully using Beebe's First Steps. It has many admi- 
rable qualities."— Sup't N. L. Bishop, Norwich, Conn. 

" I think it especially excellent for a system of graded schools, where 
uniformity of teaching is essential. It develops in practical shape an idea 
that I have long sustained as to the proper method of teaching arithmetic." 
Sup't B. B. Snow, Auburn, N. Y. 

"I have recommended Beebe's First Steps as the best work in primary 
arithmetic. . . . The book is received with much favor, and is very helpful 
to me in my work."— Prof. A. N. Husted, State Normal School, Albany, N Y. 

"I am much pleased with the book, and wish every primary teacher to 
have a copy."— Sup't J. M. Frost, Hudson, N. Y. 

"By vote of the Board of Education a copy of the Teachers' Edition 
was placed on the desk of every primary teacher in the city.— Sup't Edward 
Smith, Syracuse, N. Y. 

" I consider Beebe's First Steps the best work of the kind that I have 
ever seen, and I take every opportunity to recommend it."— Mary L. Sutliff, 
Haiku, Maui, Hawaian Islands, Feb. 9, 1888. 

2 The Pestalozzian Series of Arithmetics. Teachers' Manual and First- 
Year Text-Book for pupils in the first grade. Based upon Pestalozzi's 
method of teaching Elementary Number. By James H. Hoose. Boards, 
16mo, 2 editions. Pupils' Edition, pp. 156, 35 cts. Teacher's Edition, contain- 
ing the f orcner, with additional matter, pp. 217, 50 cts. 

This is a practical exposition of the Pestalozzian Method, and has met with 
great success not only in the Cortland Normal School, where it was first 
developed, but in many other leading schools, as at Gloversville, Babylon, 
etc. It is diametrically opposed to the Grube Method, and good teachers 
should be familiar with both, that they may choose intelligently between 
them. 

3. Lessons in Number, as given in a Pestalozzian School, Cheam Surrey. 
The Master's Manual By C. Reiner. 16mo, pp. 224. $1.50. 

This work was prepared in 1835 under the supervision of Dr. C Mayo in 
the first English Pestalozzian school, and has particular value as represent- 
ing directly the educational methods of the great reformer. 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



THE SCHOOL BULLETIN PUBLICATIONS. 

Useful Appliances in Arithmetic. 

1. The Word Method in Number. A series of 45 Cards, on which ar« 
printed all the possible Combinations of Two Figures. In box. By EL K. 
Sanford, Institute Canductor. Size 3J4 x 6 inches. Price 50 cts. 

These cards need only to be seen, as the principle is familiar and ac- 
cepted. The type, in written figures, is large enough to be seen across the 
room, and the combination on one side is given in reversed order on the 
other, so that as the teacher holds the card before him he knows the figures 
presented to the class. The pupil is taught to look upon the combination 
4-j- 9 as itself 13, not as "4 and 9 are 13," just as he looks upon DOG as an 
entire word, not as D-O-G. Success is certain if new combinations are in- 
troduced only after those already given are thoroughly learned. Reviews 
should be constant. 

2. A Fractional Apparatus. By W. W.Davis. A box of eight wooden 
balls, three and one-half inches in diameter, seven of which are sawn into 
2, 3, 4, 6, 8, 9, and 12 parts respectively, while the eighth is left a sphere. 
Price 84.00. 

With this apparatus every principle and rule can be developed, and the 
pupils can be led to deduce rules for themselves. 

Many other expedients are resorted to, but they are all objectionable. 
Suppose a teacher takes a stick and breaks it in the middle, will the pupil 
perceive two halves of a stick or two sticks? In teaching fractions object- 
ively, that should be taken for unity from which if a part is taken unity ig 
destroyed. This is not the case with a stick or cube. Apples are objection- 
able for three reasons ; first because they cannot always be obtained ; sec- 
ond because they are perishable ; and third, because the attention of the 
pupils is diverted by a desire to know whether they are sweet or sour, etc. 
Nor can the teacher readily saw wooden balls into divisions even enough for 
the purpose designed, the charm of this method being the exact presentation 
to the pupil's eye of the fact illustrated. 

3. A Manual of Suggestions for Teaching Fractions especially designed 
for accompanying the above apparatus. By W. W. Davis. Paper, l2mo, 
pp. 43. 25 cts. 

This accompanying manual gives probably the best arrangement of th« 
subject into sixty lessons ever made, with practical suggestions which all 
teachers will find valuable. 

h. Cube Root Blocks, carried to Three Places. In box. $1.00. 

Our blocks are unusually large, the inner cube being two inches, and tb« 
additions each one-half inch wide. 

5. Numeral Frame, with 100 balls, $1JK ; with 144 balls, 81.50. 

"Initiate children to arithmetic by means of the ball fr ime alone, then 
by making their elementary instruction a simple and natu.al exten ?ion of 
their own daily observation,*' says Laurie, in his standard book on Primary 
Instruction (p. 112), and as he leaves the subject of arithmetic, he adds thia 
note (p. 117), as if in fear he had not been sufficiently emphatic : 

" The teaching of arithmetic should be begun earlier than is customary, 
and always with the ball-frame.'" 

C. W. BARDEEN, Publisher, Syracuse, IT. Y, 



THE SCHOOL BULLETIN PUBLICATIONS. 



M eiklejohn (J. M. D.) The New Education. 16ino, pp. 35 15 

Maps* for the Wall. New York Stale, 2y 2 x 3 feet. Taper, §1.00. Cloth 2 00 

The Same, 68x74 inches, cloth 10 00 

United States, colored by States and counties, 3;4x5 feet, with Chart 3 00 

^Hemispheres, N. Am., S. Am., Europe, Aaia, Africa, U. S. Political,!!. S. 

Historical, (Johnston's) 40x48, cloth, each 5 00 

— Dissected M aps. United States sawn into States 75 

The same, New York State sawn into Counties 75 

Michael (O. 8.) Algebrafor Beginners. Cloth, lbnio, pp. 120 75 

Miller (Warner.) Education as a Dep't of Government. Paper, 8vo, pp. 12. 15 

Mills (C. D. B.) The Tree of Mythology. Cloth, 8vo, Pp.281 3 00 

Milton (John) A Small Tractate of Education. Paper, 16mo, pp. 26 15 

Mottoes for the School Room. Per set of 24, 12 cards, 7x14 1 00 

Natural History of the State of New York. 26 volumes 4to. 

-[Reports on the Cabinet of Natural History 35 volumes, 8vo, and 4to. 

Write for information as to the above. 

New York State Examination Questions. Cloth, 16mo, pp. 256 50 

The Questions in Book-Keeping, with Answers. Paper, 16mo, pp . 31 10 

Northam (Henrv C.) Civil Government. Cloth, 16mo, pp. 185 71 

Fixing the Facts of American History. Cloth, 12mo, pp. 3<>0 75 

Conversational Lessons Leading to Geography, lnmo, pp. 39 25 

Northend (Chas.) Memory Selections. Three series. Each 25 

Northrop (B. G.) High Schools. Paper,8vo, pp. 26 25 

Northmp (A. J.) Camps and Tramps in the Adirondacks. 16mo, pp. 302. 

Paper, 50 cents ; in Cloth 1 25 

Number Lessons. On card-board, 7x11, after the Grube Method 10 

Papers on School Issues of the Day. 8 numbers, each 15 

Payne (Joseph.) Lectures on the Art of Education. Cloth, 16mo, pp. 281.. 1 00 
Pardon (Emma L.) Oral Instruction in Geography. Paper, 16mo, pp. 29 — 15 
Payne (W. H.) A Short History of Education. Cloth, 16mo, pp. 105.... 50 

Pedagogical Biography. 16mo, paper, each 15 

I. The Jesuits, Ascham, Montaigne, Ratich, Milton. 
II. John Amos Comenius. III. John Locke. 

IV. Jean Jacques Rousseau. V. John Bernard Basedow. 

VI. Joseph Jacotot. VII. John Henrv Pestalozzi. 

Perez (B.) The First Three Years of Childhood. With an introduction by 

Prof. Sully. Cloth, 12mo. pp.294 150 

Periodicals. The Sclwol Bulletin. Monthlv, 16 pp., 10x14. Per year 100 

Bound Vols. I-XIV. Cloth, 200pp., each*. 2 00 

The School Room. Bound volumes I-V. Each 1 50 

Phillips (Philip.) Song Life. Oblong, boards, pp. 176 50 

Pooler (Chas. T.) Chart of Civil Government. Cloth 25 

The Same, in sheets 12x18. per hundred 5 00 

Hmts on Teaching Orthoepy. Paper, 12mo, pp. 15 10 

Postage-Stamp Photographs. Taken from photograph of any size. Per 100. 1 50 

Quick (K. H.) Essay* on Educational Reformers. Cloth, 12mo, pp., 331 1 50 

* Regents' Examination Paper. Six styles. Per ream, SI .75 to 2 50 

Regents' Examination Record. Cards, per hundred 50 

The same on sheets 5 to page, 72 pages for 720 scholars, hound, 2 50 

The same on sheet 5 to page, 144 pages for 1440 scholars, bound 3 00 

Regents' .Examination Syllabus, In U. S. History. Paper, per dozen... 50 
Regents' Questions. To June. 1882. (No later are printed). Eleven V. 

1. Complete with Key. The Regents' Questions from the first exam- 
ination in 1865. Cloth, l6mo, pp. 476 2 06 

2. Complete. The same as the above but without the answers. Pp.333. 1 00 
8. Arithmetic. The 1.293 questions in Arithmetic. Pp.93 25 

4. Key to Arithmetic. Answers to the above. Manilla, lOmo, pp. 20 25 

5. Thousand Regents' Questions in Arithmetic. Card-hoard 100 

6. Geography, The 1,9S7 questions in Oeography. Pp.70 25 

7. Key to Geography. Answers to the above. Manilla. l6mo, | 

8. Grammar. The 2,976 questions In Grammar. Manilla, i6mo, pp. 109 25 

9. Grammar and Key. Cloth, lfinio, pp. 198 1 00 

11. Key to Grammar. Manilla, 16mo, pp. 8<* 25 

10. Spelling. The 1.800 words given in Spelling. Manilla, lflmo, pp. 81. ?5 

Richardson (B. W.) Learning and Health. Paper, IBmo, pp. 39 15 

Roe (Martha.) A Work in Number. Cloth, 12mo, pp. 180 50 

Roget (P.M.) Thesaurus of English Words and Phrases. CI., 12mo. pp. 800 2 00 

Ryan (d. TV.) School Record. 5fi blanks on each of 14 sheets 50 

Sanford (H. R.) The Word Method in Number. Per box of 45 cards. 50 



C. W. BARDEEN, PUBLISHER, SYRACUSE, 



School Room Classics. 11 vols. Paper, 16mo, pp. about 40 15 



I. Huntington's Unconscious Tuition. 
II. Fitch's Art of Questioning. 

III. Kennedy's Philosophy of School 

Discipline. 

IV. Fitch's Art of Securing Attention. 
V. Richardson's Learning and Health. 

VI. Meikeljohn's New Education. 



VII. Milton's Tractate of Education. 
VIII. Von Buelow's School Workshop. 
IX. Maudsley's Sex in Mind and in 

Education. 
X. Education asViewed by Thinkers. 
XI. Harris's How to Teach Natural 
Science in the Public Schools. 



Shaw's Scholar's Register, Paper, 5x7, pp. 16. Per dozen 50 

Sheely (Aaron) Anecdotes and Humors of School Life. Cloth, 12mo, pp. 350 1 50 

Sherrill (J. E.) The Normal Question Book. Cloth. 12mo, pp. 405 1 50 

Shirreff (Emily). The Kindergarten System. Cloth, 12mo, pp. 200 100 

*Slate Pencil Blackboard Slating. Gallons, covering 600 ft., one coat 10 00 

Slated Paper, per square yard (if by mail, 60 cts) .- 50 

Smith (C. F.) Honorary Degrees as conferred in American Colleges. Paper, 

8vo, pp. 9 15 

Song Century, The. One Hundred Standard Songs for School and Home. 

l6mo, pp. 64. (Com panion to the Song Budget) 15 

Somberger (S. J.) Normal Language Lessons, Boards, 16mo, pp. 75 50 

Southwiek (A. P.) Twenty Dime Question Books, with full answers, notes, 

queries, etc. Paper, l6mo, pp. about 40. Each 10 



Advanced Series* 

1. Physics. 

2. General Literature. 
5. General History. 

7. Astronomy. 

8. Mythology. 

9. Rhetoric. 

11. Botany. 

12. Zoology. 

16. Chemistry. 

17. Geology. 



Elementary Series. 

3. Physiology. 

4. Theorv and Practice. 
6. U. S. History and Civil Gov't. 

10. Algebra. 

13. American Literature. 

14. Grammar 

15. Orthography and Etymology 
IS. Arithmetic. 

19. Physical and Political Geog. 

20. Reading an. I Punctuation. 

The 10 in one book, cloth, $1.00. The 10 in one book, cloth, $1.00. 

Extra Numbers 21. Temperance Physiology; 22. Book-Keeping; 23. 

Letter- Writing. Each .- 10 

Quizzism. Quirks and Quibbles from Queer Quarters. 16mo, pp. 25.... 25 

- —A Quiz Book of Theory and Practice. Cloth, 12mo, pp. 220 1 00 

Starkweather (Asher) An Aid to English Grammar. 16mo, pp. 216 75 

Stoweil (T. B.) Syllabus of Lectures on Physiology. Boards, 8vo, pp. 133.. 1 00 

Straight (H. H.) Aspects of Industrial Education. Paper, 8vo, pp.12 15 

Swett (John) Manual of Elocution. Cloth, 12mo, pp. 300, net 150 

Tate (Thos.) The Philosophy of Education. Cloth, 12mo, pp. 330 1 50 

Taylor (H. F-) Union School Record Cards 5>:8 inches. Per hundred 2 00 

Thomas (Flave! S.) University Degrees. Paper, 16mo, pp. 40 15 

Thompson (D'Arcy W.) Day Dreams of a Schoolmaster. 16mo, pp. 328. .. 1 25 

Thousand Questions in U. S. History. Cloth, 16mo, pp. 200 1 00 

Tillinghast (Wm.) The Diadem of School Songs. Boards, 4to, pp. 160. ... 50 

Underwood (L. M.) Systematic Plant Record. Manilla, 7x8J4 pp. 52 30 

Uniform Examination Questions, New York. All Questions from the 
beginning to March 1889, are published as follows : 

I. Arithmetic, 317 Questions, 10 cents. II. Key, 10 cents. 

III. Geography, 709 " " IV. « l " 

V. Grammar, 533 " " VI. " " 

VII. U. S. History, 429 " " VIII. " 

IX. Civil Government 354 " " X. " " 

XL Physiology, 345 H ■« XII. " 

Valentine (S. Louise.) Numbers Made Easy. In box, with Key 50 

Van Wie (C. B.) Outlines in U. S. History. Paper, 16mo,pp. 40 and map 15 
Welch (Emma A.) Intermediate Arithmetic Problems. Cloth, l6mo, pp. 172 75 

Key to the, above, Cloth, 16mo, pp. 30 50 

Wells (C. R.) Improved Practical Methods in Penmanship. Nos. 1-4, Each.. . 10 

A Lesson on Ann Movement in Writing. Paper, 8vo, pp. 32 25 

Williams (Geo. A.) Topics in American History. Cloth, 16mo, pp. 50.... 50 
Any of the above not starred sent post-paid on receipt of the price. 

C. W. BARDEEN, Publisher, Syracuse, N. Y. 



